Metallocene-produced very low density polyethylenes

ABSTRACT

The present invention provides a polymer blend suitable for use as a film or a coating, the polymer blend including from 1 to 99% by weight of a metallocene-produced VLDPE polymer having a density less than 0.916 g/cm 3 , and from 1 to 99% by weight of an LDPE polymer having a density of from 0.916 to 0.928 g/cm 3  wherein the sum of (a) and (b) is 100%. The VLDPE polymer can have a melt index of from 6 to 15 dg/min, or from 9 to 12 dg/min. The present invention further provides polymeric films extrusion cast from such polymer blends, and articles having a flexible substrate and a polymeric film extrusion-coated on the substrate

This application claims the benefit of U.S. Provisional Application No.60/213,571, filed Jun. 22, 2000; U.S. Provisional Application No.60/243,208, filed Oct. 25, 2000; U.S. Provisional Application No.60/270,802, filed Feb. 23, 2001; U.S. Provisional Application No.60/278,560, filed Mar. 23, 2001; U.S. Provisional Application No.60/278,315, filed Mar. 23, 2001; and U.S. Provisional Application No.60/278,567 filed Mar. 23, 2001, the entire disclosures of which arehereby incorporated by reference.

1. FIELD OF THE INVENTION

The present invention relates generally to very low density polyolefinsand films produced from very low density polyolefins. More specifically,the present invention is directed to very low density polyethylenesproduced using metallocene catalysts, and cast extrusion films formed ofmetallocene-very low density polyethylenes having improved sealing andmechanical properties relative to conventional low density polyethylenefilms.

2. BACKGROUND

A variety of polymeric materials have been used successfully in thincast films. A typical film casting process includes the steps of polymerextrusion, melt feeding through a slot die, melt draw-down in the airgap, chill-roll casting, edge-trim slitting, surface treating ifnecessary, and winding. The polyolefin film can be extruded onto asubstrate of paper, metal foil, or other flexible substrate material toform an extrusion coated substrate. Extrusion of multiple layers ofpolymeric materials, including polyolefins as well as other materials, aprocess sometimes termed “coextrusion”, is also well known.

A variety of polymerization processes have been used to makepolyolefins, including polyethylene and polypropylene, suitable forextrusion coating applications. Such processes include gas-phasepolymerization, solution polymerization and bulk polymerization. Morespecifically, gas phase polymerization processes using Ziegler-Natta orvanadium-based catalyst systems have been used to make “low densitypolyethylenes” (“LDPEs”), i.e., polyethylenes having densities of from0.916 to 0.928 g/cm³; “medium density polyethylenes” (“MDPEs”), i.e.,polyethylenes having densities of from 0.929 to 0.940 g/cm³; and “highdensity polyethylenes” (“HDPEs”), i.e., polyethylenes having densitiesgreater than 0.940.

The low density polyethylene extrusion coating market is dominated byconventional LDPE made in a high-pressure process. LDPE is generallypreferred because it is easy to extrude, has high melt strength therebyminimizing neck-in, and has good sealing characteristics. Linear lowdensity polyethylene (“LLDPE”) offers improved coating toughness, butits relatively narrow molecular weight distribution makes it moredifficult to extrude, and it has relatively poor sealing properties;LLDPE makes up about 5% of the low density polyethylene extrusionmarket.

Although LDPE and LLDPE are widely used, these materials suffer fromseveral disadvantages in extrusion coating applications. In applicationsrequiring adhesion of a coating to polypropylene, LDPE and LLDPE offerrelatively poor adhesion, thus necessitating the extra expense andcomplexity of an adhesive or tic layer. It would thus be desirable tohave a polyethylene-based extrusion coating material capable of improvedadhesion to polypropylene substrates. In addition, it would be desirableto have an extrusion coating material offering improved mechanicalproperties and improved sealing performance. Further, it would bedesirable to have an extrusion coating material capable of being formedin thinner layer than is conventionally possible with LDPE and LLDPE.Still farther, it would be desirable to have an extrusion coatingmaterial providing better organoleptic properties than LLDPE.

U.S. Pat. No. 5,382,631 discloses linear interpolymer blends made fromcomponents having narrow molecular weight distribution (e.g. Mw/Mn≦3)and a narrow composition distribution (e.g. CDBI>50%/). The blends haveeither Mw/Mn>3 and/or CDBI<50%, and combinations of each, and can bebimodal with respect to either or both molecular weight and/or comonomercontent. The blends are generally free of blend components having both ahigher average molecular weight and a lower average comonomer contentthan another blend component.

3. SUMMARY OF THE INVENTION

In one embodiment, the present invention is directed to a polymer blend,the blend including a very low density polyethylene (VLDPE) polymerhaving a density of less than 0.916 g/cm³, and a low densitypolyethylene (LDPE) polymer, having a density of from 0.916 to 0.940g/cm³. Preferably the VLDPE and LDPE polymers are metallocene-catalyzedpolymers.

In another embodiment, the present invention provides a polymer blendsuitable for use as a film or a coating, the polymer blend includingfrom 1 to 99% by weight of a metallocene-produced VLDPE polymer having adensity less than 0.916 g/cm³, and from 1 to 99% by weight of an LDPEpolymer having a density of from 0.916 to 0.928 g/cm³ wherein the sum ofVLDPE and the LDPF is 100%. Alternatively, the blend can have from 5 to95%, from 10 to 90%, or from 15 to 85% by weight of the LDPE polymer.The VLDPE polymer can have a melt index of from 6 to 15 dg/min, or from9 to 12 dg/min. The VLDPE polymer can be an ethylene homopolymer, or acopolymer of ethylene and a C₃ to C₁₂ alpha-olefin. The LDPE polymer canhave a melt index of from 0.5 to 15 dg/min, or from 1 to 10 dg/min. TheLDPE polymer can be an ethylene homopolymer, or a copolymer of ethyleneand a C₃ to C₁₂ alpha-olefin.

In another embodiment, the present invention is directed to a polymerblend, the blend including a gas-phase metallocene-produced VLDPEpolymer, the VLDPE polymer being a copolymer of ethylene and at leastone C₃ to C₁₂ alpha olefin and having a density of from 0.900 to 0.915g/cm³ and a melt index of from 5 to 20 g/10 min; and ametallocene-produced LDPE polymer, the LDPE polymer being a copolymer ofethylene and at least one C₃ to C₁₂ alpha olefin and having a density offrom 0.916 to 0.940 g/cm³ and a melt index of from 0.5 to 15 g/10 min.In this embodiment, the blend includes 5-95% by weight of the VLDPEpolymer and 95-5% by weight of the LDPE polymer, based on the totalweight of the VLDPE and LDPE polymers.

In another embodiment, the present invention is directed to a polymerblend, the blend including a gas-phase metallocene-produced VLDPEpolymer, the VLDPE polymer being a copolymer of ethylene and 1-butene,1-hexene or 1-octene and having a density of from 0.910 to 0.915 g/cm³,a melt index of from 5 to 20 g/10 min, a composition distributionbreadth index (CDBI) of 60 to 80 wt % and a molecular weightdistribution (MWD) of 2.2 to 2.8; and a metallocene-produced LDPEpolymer, the LDPE polymer being a copolymer of ethylene and 1-butene,1-hexene or 1-octene and having a density of from 0.916 to 0.925 g/Cm³and a melt index of from 0.5 to 10 g/10 min. In this embodiment, theblend preferably includes 10-90% by weight of the VLDPE polymer and90-10% by weight of the LDPE polymer, based on the total weight of theVLDPE and LDPE polymers.

In one embodiment, the present invention is directed to a VLDPE/LDPEpolymer blend, the blend including a metallocene-produced VLDPE polymercomprising an ethylene copolymer with a comonomer content of 25% or lessby weight, preferably 20% or less by weight, and more preferably 15% orless by weight.

In another embodiment, the present invention is directed to a polymerblend, the blend including from 1 to 99% by weight of a copolymerderived from ethylene and one or more C₃-C₂₀ alpha olefin comonomers,and from 1 to 99% by weight of a low density polyethylene polymer havinga density of from 0.916 to 0.928 g/cm³, wherein the sum of the weight ofthe copolymer and low density polyethylene polymer is 100%. Thecopolymer is further characterized by properties including one or moreof the following: a comonomer content of from 5 to 15 wt. %, a densityof less than 0.916 g/cm³, a composition distribution breadth index inthe range of from 55% to 70%, a molecular weight distribution Mw/Mn offrom 2 to 3, and a molecular weight distribution Mz/Mw of less than 2.

In another embodiment, the present invention is directed to an article,the article including a substrate and a film disposed on the substrate.The film includes a polymer blend, the polymer blend including from 1 to99% by weight of a copolymer derived from ethylene and one or moreC₃-C₂₀ alpha olefin comonomers, and from 1 to 99% by weight of a lowdensity polyethylene polymer having a density of from 0.916 to 0.928g/cm³, wherein the sum of the weight of the copolymer and the lowdensity polyethylene polymer is 100%. The copolymer is furthercharacterized by properties including one or more of the following: acomonomer content of from 5 to 15 wt. %, a density of less than 0.916g/cm³, a composition distribution breadth index in the range of from 55%to 70%, a molecular weight distribution Mw/Mn of from 2 to 3, and amolecular weight distribution Mz/Mw of less than 2.

In another embodiment, the present invention is directed to a polymerblend composition, the composition including (a) a copolymer derivedfrom ethylene and one or more C₃-C₂₀ alpha olefin comonomers and (b) alow density polyethylene polymer having a density of from 0.916 to 0.928g/cm³. The copolymer is further characterized by properties includingone or more of the following: a comonomer content of from 5 to 15 wt. %,a density of less than 0.916 g/cm³, a composition distribution breadthindex in the range of from 55% to 70%, a molecular weight distributionMw/Mn of from 2 to 3, a molecular weight distribution Mw/Mw of less than2, and a bi-modal composition distribution.

In another embodiment, the present invention is directed to a monolayerfilm formed from a blend including (a) a copolymer derived from ethyleneand one or more C₃-C₂₀ alpha olefin comonomers and (b) a low densitypolyethylene polymer having a density of from 0.916 to 0.928 g/cm³. Thecopolymer is further characterized by properties including one or moreof the following: a comonomer content of from 5 to 15 wt. %, a densityof less than 0.916 g/cm³, a composition distribution breadth index inthe range of from 55% to 70%, a molecular weight distribution Mw/Mn offrom 2 to 3, a molecular weight distribution Mz/Mw of less than 2, and abi-modal composition distribution.

In another embodiment, the present invention is directed to a multilayerfilm, the film including a first layer and a second layer, and at leastone of the layers including a polymer blend composition. The polymerblend composition includes (a) a copolymer derived from ethylene and oneor more C₃-C₂₀ alpha olefin comonomers and (b) an LDPE polymer having adensity of from 0.916 to 0.928 g/cm³. The copolymer is furthercharacterized by properties including one or more of the following: acomonomer content of from 5 to 15 wt. %, A density of less than 0.916g/cm³, a composition distribution breadth index in the range of from 55%to 70%, a molecular weight distribution Mw/Mn of from 2 to 3, amolecular weight distribution Mz/Mw of less than 2, and a bi-modalcomposition distribution.

In another embodiment, the present invention is directed to a polymerblend composition, the composition including a metallocene-catalyzedlinear very low density polyethylene polymer and a low densitypolyethylene polymer having a density of from 0.916 to 0.928 g/cm³. Thevery low density polyethylene polymer is further characterized byproperties including one or more of the following: a density of lessthan 0.916 g/cm³, a composition distribution breadth index of 50 to 85%by weight, a molecular weight distribution Mw/Mn of 2 to 3, and amolecular weight distribution Mz/Mw of less than 2.

Polyethylene has Two Peaks in a TREF Measurement

In another embodiment, the present invention provides a polymeric film,the film being extrusion cast from a blend of a metallocene-producedVLDPE polymer and an LDPE, as described above.

In another embodiment, the present invention is directed to monolayerfilms formed from the polymer blends of the invention.

In another embodiment, the present invention is directed to multilayerfilms, wherein at least one layer of the multilayer film is formed of apolymer blend of the invention.

In other embodiments, the invention is directed to articles includingthe films of the invention, articles wrapped with the films of theinvention, and substrates coated with the films of the invention.

In another embodiment, the present invention provides an article ofmanufacture, the article including a flexible substrate and a polymericfilm extrusion-coated on the substrate, wherein the polymeric film is ablend of a metallocene-produced VLDPE polymer and an LDPE as describedabove. The substrate can be a flexible material, such as paper, a metalfoil, a flexible polymeric material, or other flexible substrate capableof being coated.

The blends and films of the present invention show improved mechanicaland/or sealing properties, relative to prior art LDPE and LLDPEmaterials.

4. DETAILED DESCRIPTION

4.1 VLDPE Polymers

The polymer blends and films of the present invention include a very lowdensity polyethylene (VLDPE) polymer. As used herein, the terms “verylow density polyethylene” polymer and “VLDPE” polymer refer to apolyethylene homopolymer or preferably copolymer having a density ofless than 0.916 g/cm³. Polymers having more than two types of monomers,such as terpolymers, are also included within the term “copolymer” asused herein. The comonomers that are useful in general for making VLDPEcopolymers include α-olefins, such as C₃-C₂₀ α-olefins and preferablyC₃-C₁₂ α-olefins. The α-olefin comonomer can be linear or branched, andtwo or more comonomers can be used, if desired. Examples of suitablecomonomers include linear C₃-C₁₂ α-olefins, and α-olefins having one ormore C₁-C₃ alkyl branches, or an aryl group. Specific examples includepropylene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene;1-pentene with one or more methyl, ethyl or propyl substituents;1-hexene with one or more methyl, ethyl or propyl substituents;1-heptene with one or more methyl, ethyl or propyl substituents;1-octene with one or more methyl, ethyl or propyl substituents; 1-nonenewith one or more methyl, ethyl or propyl substituents; ethyl, methyl ordimethyl-substituted 1-decene; 1-dodecene; and styrene. It should beappreciated that the list of comonomers above is merely exemplary, andis not intended to be limiting. Preferred comonomers include propylene,1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and styrene.

Other useful comonomers include conjugated and non-conjugated dienes,acetylene, which can be included in minor amounts in terpolymercompositions. Non-conjugated dienes useful as co-monomers preferably arestraight chain, hydrocarbon di-olefins or cycloalkenyl-substitutedalkenes, having 6 to 15 carbon atoms. Suitable non-conjugated dienesinclude, for example: (a) straight chain acyclic dienes, such as1,4-hexadiene and 1,6-octadiene; (b) branched chain acyclic dienes, suchas 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene; and3,7-dimethyl-1,7-octadiene; (c) single ring alicyclic dienes, such as1,4-cyclohexadiene; 1,5-cyclo-octadiene and 1,7-cyclododecadiene; (d)multi-ring alicyclic fused and bridged ring dienes, such astetrahydroindene; norbornadiene; methyl-tetrahydroindene;dicyclopentadiene (DCPD); bicyclo-(2.2.1)-hepta-2,5-diene; alkenyl,alkylidene, cycloalkenyl and cycloalkylidene norbornenes, such as5-methylene-2-norbornene (MNB), 5-propenyl-2-norbornene,5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-norbornene,5-cyclohexylidene-2-norbornene, and 5-vinyl-2-norbornene (VNB); and (e)cycloalkenyl-substituted alkenes, such as vinyl cyclohexene, allylcyclohexene, vinyl cyclooctene, 4-vinyl cyclohexene, allyl cyclodecene,and vinyl cyclododecene. Of the non-conjugated dienes typically used,the preferred dienes are dicyclopentadiene, 1,4-hexadiene,5-methylene-2-norbornene, 5-ethylidene-2-norbornene, andtetracyclo-(Δ-11,12)-5,8-dodecene. Particularly preferred diolefins are5-ethylidene-2-norbornene (ENB), 1,4-hexadiene, dicyclopentadiene(DCPD), norbornadiene, and 5-vinyl-2-norbornene (VNB). Note thatthroughout this description the terms “non-conjugated diene” and “diene”are used interchangeably.

It should be appreciated that the amount of comonomer used will dependupon the desired density of the VLDPE polymer and the specificcomonomers selected. In general, the comonomer will be present in anamount of from 0 to 15% by weight, typically 5 to 15% by weight forpreferred comonomers such as butene, hexene and octene. It iswell-understood in the art that, for a given comonomer, the density ofthe VLDPE polymer produced therefrom decreases as the comonomer contentincreases. One skilled in the art can readily determine the appropriatecomonomer content appropriate to produce a VLDPE polymer having adesired density.

The VLDPE polymer has a density of less than 0.916 g/cm³, and preferablyat least 0.890 g/cm³, more preferably at least 0.900 g/cm³. Thus, apreferred density range for the VLDPE polymer is 0.900 g/cm³ to 0.915g/cm³. Alternate lower limits of the VLDPE polymer density include 0.905g/cm³ or 0.910 g/cm³.

The VLDPE polymer is further characterized by a melt index (MI) of from0.5 to 20 g/10 min (dg/min), as measured in accordance with ASTM-1238condition E. In one or more specific embodiments, alternative lowerlimits for the melt index include 0.7 and 1.0 g/10 min, and alternativeupper limits for the melt index include 5, 10 and 15 g/10 min, with meltindex ranges from any lower limit to any upper limit being within thescope of the invention.

In one embodiment, the VLDPE polymer is made in a metallocene-catalyzedpolymerization process. As used herein, the terms “metallocene-catalyzedVLDPE,” “metallocene-produced VLDPE,” or “m-VLDPE” refer to a VLDPEpolymer having the density and melt index properties described herein,and being produced in the presence of a metallocene catalyst. Oneskilled in the art will recognize that a metallocene-catalyzed VLDPEpolymer has measurable properties distinguishable from a VLDPE polymerhaving the same comonomers in the same weight percentages but producedfrom a different process, such as a conventional Ziegler-Nattapolymerization process.

The terms “metallocene” and “metallocene catalyst precursor” as usedherein mean compounds having a Group 4, 5 or 6 transition metal (M),with a cyclopentadienyl (Cp) ligand or ligands which may be substituted,at least one non-cyclopentadienyl-derived ligand (X), and zero or oneheteroatom-containing ligand (Y), the ligands being coordinated to M andcorresponding in number to the valence thereof. The metallocene catalystprecursors generally require activation with a suitable co-catalyst(referred to as an “activator”), in order to yield an “activemetallocene catalyst”, i.e., an organometallic complex with a vacantcoordination site that can coordinate, insert, and polymerize olefins.The metallocene catalyst precursor is preferably one of, or a mixture ofmetallocene compounds of either or both of the following types:

(1) Cyclopentadienyl (Cp) complexes which have two Cp ring systems forligands. The Cp ligands form a sandwich complex with the metal and an befree to rotate (unbridged) or locked into a rigid configuration througha bridging group. The Cp ring ligands can be like or unlike,unsubstituted, substituted, or a derivative thereof, such as aheterocyclic ring system which may be substituted, and the substitutionscan be fused to form other saturated or unsaturated rings systems suchas tetrahydroindenyl, indenyl, or fluorenyl ring systems. Thesecyclopentadienyl complexes have the general formula

(Cp¹R¹ _(m))R³ _(n)(Cp²R² _(p))MX_(q)

wherein: Cp¹ and Cp² are the same or different cyclopentadienyl rings;R¹ and R² are each, independently, a halogen or a hydrocarbyl,halocarbyl, hydrocarbyl-substituted organometalloid orhalocarbyl-substituted organometalloid group containing up to about 20carbon atoms; m is 0 to 5; p is 0 to 5; two R¹ and/or R² substituents onadjacent carbon atoms of the cyclopentadienyl ring associated therewithcan be joined together to form a ring containing from 4 to about 20carbon atoms; R³ is a bridging group; n is the number of atoms in thedirect chain between the two ligands and is 0 to 8, preferably 0 to 3; Mis a transition metal having a valence of from 3 to 6, preferably fromgroup 4, 5, or 6 of the periodic table of the elements and is preferablyin its highest oxidation state; each X is a non-cyclopentadienyl ligandand is, independently, a halogen or a hydrocarbyl, oxyhydrocarbyl,halocarbyl, hydrocarbyl-substituted organometalloid,oxyhydrocarbyl-substituted organometalloid or halocarbyl-substitutedorganometalloid group containing up to about 20 carbon atoms; and q isequal to the valence of M minus 2.

(2) Monocyclopentadienyl complexes which have only one Cp ring system asa ligand. The Cp ligand forms a half-sandwich complex with the metal andcan be free to rotate (unbridged) or locked into a rigid configurationthrough a bridging group to a heteroatom-containing ligand. Bridgedstructures can be meso-configurations or racemic stereoisomers, or amixture thereof. The Cp ring ligand can be unsubstituted, substituted,or a derivative thereof such as a heterocyclic ring system which may besubstituted, and the substitutions can be fused to form other saturatedor unsaturated rings systems such as tetrahydroindenyl, indenyl, orfluorenyl ring systems. The heteroatom containing ligand is bound toboth the metal and optionally to the Cp ligand through the bridginggroup. The heteroatom itself is an atom with a coordination number ofthree from group 15 or 16 of the periodic table of the elements. Thesemono-cyclopentadienyl complexes have the general formula

(Cp¹R¹ _(m))R³ _(n)(Y_(r)R²)MX_(s)

wherein: each R¹ is independently, a halogen or a hydrocarbyl,halocarbyl, hydrocarbyl-substituted organometalloid orhalocarbyl-substituted organometalloid group containing up to about 20carbon atoms, “m” is 0 to 5, and two R¹ substituents on adjacent carbonatoms of the cyclopentadienyl ring associated there with can be joinedtogether to form a ring containing from 4 to about 20 carbon atoms; R³is a bridging group; “n” is 0 to 3; M is a transition metal having avalence of from 3 to 6, preferably from group 4, 5, or 6 of the periodictable of the elements and is preferably in its highest oxidation state;Y is a heteroatom containing group in which the heteroatom is an elementwith a coordination number of three from Group VA or a coordinationnumber of two from group VIA, preferably nitrogen, phosphorous, oxygen,or sulfur; R² is a radical selected from a group consisting of C₁ to C₂₀hydrocarbon radicals, substituted C₁ to C₂₀ hydrocarbon radicals,wherein one or more hydrogen atoms is replaced with a halogen atom, andwhen Y is three coordinate and unbridged there may be two R² groups on Yeach independently a radical selected from the group consisting of C₁ toC₂₀ hydrocarbon radicals, substituted C₁ to C₂₀ hydrocarbon radicals,wherein one or more hydrogen atoms is replaced with a halogen atom, andeach X is a non-cyclopentadienyl ligand and is, independently, a halogenor a hydrocarbyl, oxyhydrocarbyl, halocarbyl, hydrocarbyl-substitutedorganometalloid, oxyhydrocarbyl-substituted organometalloid orhalocarbyl-substituted organometalloid group containing up to about 20carbon atoms, “s” is equal to the valence of M minus 2.

Examples of biscyclopentadienyl metallocenes of the type described ingroup (1) above for producing the m-VLDPE polymers of the invention aredisclosed in U.S. Pat. Nos. 5,324,800; 5,198,401; 5,278,119; 5,387,568;5,120,867; 5,017,714; 4,871,705; 4,542,199; 4,752,597; 5,132,262;5,391,629; 5,243,001; 5,278,264; 5,296,434; and 5,304,614.

Illustrative, but not limiting, examples of suitable bridgedbiscyclopentadienyl metallocenes of the type described in group (1)above are the racemic isomers of:

μ-(CH₃)₂Si(indenyl)₂M(Cl)₂;

μ-(CH₃)₂Si(indenyl)₂M(CH₃)₂;

μ-(CH₃)₂Si(tetrahydroindenyl)₂M(Cl)₂;

μ-(CH₃)₂Si(tetrahydroindenyl)₂M(CH₃)₂;

μ-(CH₃)₂Si(indenyl)₂M(CH₂CH₃)₂; and

μ-(C₆H₅)₂C(indenyl)₂M(CH₃)₂;

wherein M is Zr or Hf.

Examples of suitable unsymmetrical cyclopentadienyl metallocenes of thetype described in group (1) above are disclosed in U.S. Pat. Nos.4,892,851; 5,334,677; 5,416,228; and 5,449,651; and in the publicationJ. Am. Chem. Soc. 1988, 110, 6255.

Illustrative, but not limiting, examples of preferred unsymmetricalcyclopentadienyl metallocenes of the type described in group (1) aboveare:

μ-(C₆H₅)₂C(cyclopentadienyl)(fluorenyl)M(R)₂;

μ-(C₆H₅)₂C(3-methylcyclopentadienyl)(fluorenyl)M(R)₂;

μ-(CH₃)₂C(cyclopentadienyl)(fluorenyl)M(R)₂;

μ-(C₆H₅)₂C(cyclopentadienyl)(2-methylindenyl)M(CH₃)₂;

μ-(C₆H₅)₂C(3-methylcyclopentadienyl)(2-methylindenyl)M(Cl)₂;

μ-(C₆H₅)₂C(cyclopentadienyl)(2,7-dimethylfluorenyl)M(R)₂; and

μ-(CH₃)₂C(cyclopentadienyl)(2,7-dimethylfluorenyl)M(R)₂;

wherein M is Zr or Hf, and R is Cl or CH₃.

Examples of suitable monocyclopentadienyl metallocenes of the typedescribed in group (2) above are disclosed in U.S. Pat. Nos. 5,026,798;5,057,475; 5,350,723; 5,264,405; 5,055,438; and in WO 96/002244.

Illustrative, but not limiting, examples of preferredmonocyclopentadienyl metallocenes of the type described in group (2)above are:

μ-(CH₃)₂Si(cyclopentadienyl)(1-adamantylamido)M(R)₂;

μ-(CH₃)₂Si(3-tertbutylcyclopentadienyl)(1-adamantylamido)M(R)₂;

μ-(CH₂(tetramethylcyclopentadienyl)(1-adamantylamido)M(R)₂;

μ-(CH₃)₂Si(tetramethylcyclopentadienyl)(1-adamantylamido)M(R)₂;

μ-(CH₃)₂C(tetramethylcyclopentadienyl)(1-adamantylamido)M(R)₂;

μ-(CH₃)₂Si(tetramethylcyclopentadienyl)(1-tertbutylamido)M(R)₂;

μ-(CH₃)₂Si(fluorenyl)(1-tertbutylamido)M(R)₂;

μ-(CH₃)₂Si(tetramethylcyclopentadienyl)(1-cyclododecylamido)M(R)₂;

and

μ-(C₆H₅)₂C(tetramethylcyclopentadienyl)(1-cyclododecylamido)M(R)₂;

wherein M is Ti, Zr or Hf, and R is Cl or CH₃.

Another class of organometallic complexes that are useful catalysts forthe VLDPE polymers described herein are those with diimido ligandsystems, such as are described in WO 96/23010.

The metallocene compounds are contacted with an activator to produce anactive catalyst. One class of activators is noncoordinating anions,where the term “noncoordinating anion” (NCA) means an anion which eitherdoes not coordinate to the transition metal cation or which is onlyweakly coordinated to the transition metal cation, thereby remainingsufficiently labile to be displaced by a neutral Lewis base.“Compatible” noncoordinating anions are those which are not degraded toneutrality when the initially formed complex decomposes. Further, theanion will not transfer an anionic substituent or fragment to the cationso as to cause it to form a neutral four coordinate metallocene compoundand a neutral by-product from the anion. Noncoordinating anions usefulin accordance with this invention are those which are compatible,stabilize the metallocene cation in the sense of balancing its ioniccharge in a +1 state, yet retain sufficient lability to permitdisplacement by an ethylenically or acetylenically unsaturated monomerduring polymerization. Additionally, the anions useful in this inventionwill be large or bulky in the sense of sufficient molecular size tolargely inhibit or prevent neutralization of the metallocene cation byLewis bases other than the polymerizable monomers that may be present inthe polymerization process. Typically the anion will have a molecularsize of greater than or equal to about 4 angstroms.

An additional method of making metallocene catalysts uses ionizinganionic pre-cursors which are initially neutral Lewis acids but form thecation and anion upon ionizing reaction with the metallocene compounds.For example, tris(pentafluorophenyl) boron acts to abstract an alkyl,hydride or silyl ligand from the metallocene compound to yield ametallocene cation and a stabilizing non-coordinating anion; see, EP-A-0427 697 and EP-A-0 520 732. Metallocene catalysts for additionpolymerization can also be prepared by oxidation of the metal centers oftransition metal compounds by anionic precursors containing metallicoxidizing groups along with the anion groups; see EP-A-0 495 375.

Examples of suitable activators capable of ionic cationization of themetallocene compounds of the invention, and consequent stabilizationwith a resulting noncoordinating anion, include:

trialkyl-substituted ammonium salts such as:

triethylammonium tetraphenylborate;

tripropylammonium tetraphenylborate;

tri(n-butyl)ammonium tetraphenylborate;

trimethylammonium tetrakis(p-tolyl)borate;

trimethylammonium tetrakis(o-tolyl)borate;

tributylammonium tetrakis(pentafluorophenyl)borate;

tripropylammonium tetrakis(o,p-dimethylphenyl)borate;

tributylammonium tetrakis(m,m-dimethylphenyl)borate;

tributylammonium tetrakis(p-trifluoromethylphenyl)borate;

tributylammonium tetrakis(pentafluorophenyl)borate; and

tri(n-butyl)ammonium tetrakis(o-tolyl)borate;

N,N-dialkyl anilinium salts such as:

N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate;

N,N-dimethylaniliniumtetrakis(heptafluoronaphthyl)borate;

N,N-dimethylanilinium tetrakis(perfluoro-4-biphenyl)borate;

N,N-dimethylanilinium tetraphenylborate;

N,N-diethylanilinium tetraphenylborate; and

N,N-2,4,6-pentamethylanilinium tetraphenylborate;

dialkyl ammonium salts such as:

di-(isopropyl)ammonium tetrakis(pentafluorophenyl)borate; and

dicyclohexylammonium tetraphenylborate; and

triaryl phosphonium salts such as:

triphenylphosphonium tetraphenylborate;

tri(methylphenyl)phosphonium tetraphenylborate; and

tri(dimethylphenyl)phosphonium tetraphenylborate.

Further examples of suitable anionic precursors include those includinga

stable carbonium ion, and a compatible non-coordinating anion. Theseinclude:

tropillium tetrakis(pentafluorophenyl)borate;

triphenylmethylium tetrakis(pentafluorophenyl)borate;

benzene (diazonium) tetrakis(pentafluorophenyl)borate;

tropillium phenyltris(pentafluorophenyl)borate;

triphenylmethylium phenyl-(trispentafluorophenyl)borate;

benzene (diazonium) phenyl-tris(pentafluorophenyl)borate;

tropillium tetrakis(2,3,5,6-tetrafluorophenyl)borate;

triphenylmethylium tetrakis(2,3,5,6-tetrafluorophenyl)borate;

benzene (diazonium) tetrakis(3,4,5-trifluorophenyl)borate;

tropillium tetrakis(3,4,5-trifluorophenyl)borate;

benzene (diazonium) tetrakis(3,4,5-trifluorophenyl)borate;

tropillium tetrakis(3,4,5-trifluorophenyl)aluminate;

triphenylmethylium tetrakis(3,4,5-trifluorophenyl)aluminate;

benzene (diazonium) tetrakis(3,4,5-trifluorophenyl)aluminate;

tropillium tetrakis(1,2,2-trifluoroethenyl)borate;

triphenylmethylium tetrakis(1,2,2-trifluoroethenyl)borate;

benzene (diazonium) tetrakis(1,2,2-trifluoroethenyl)borate;

tropillium tetrakis(2,3,4,5-tetrafluorophenyl)borate;

triphenylmethylium tetrakis(2,3,4,5-tetrafluorophenyl)borate; and

benzene (diazonium) tetrakis(2,3,4,5-tetrafluorophenyl)borate.

Where the metal ligands include halide moieties, for example,(methyl-phenyl)silylene(tetra-methyl-cyclopentadienyl)(tert-butyl-amido) zirconiumdichloride), which are not capable of ionizing abstraction understandard conditions, they can be converted via known alkylationreactions with organometallic compounds such as lithium or aluminumhydrides or alkyls, alkylalumoxanes, Grignard reagents, etc. See EP-A-0500 944, EP-A1-0 570 982 and EP-A1-0 612 768 for processes describingthe reaction of alkyl aluminum compounds with dihalide substitutedmetallocene compounds prior to or with the addition of activatinganionic compounds. For example, an aluminum alkyl compound may be mixedwith the metallocene prior to its introduction into the reaction vessel.Since the alkyl aluminum is also suitable as a scavenger (as describedbelow), its use in excess of that normally stoichiometrically requiredfor akylation of the metallocene will permit its addition to thereaction solvent with the metallocene compound. Normally, alumoxanewould not be added with the metallocene, so as to avoid prematureactivation, but can be added directly to the reaction vessel in thepresence of the polymerizable monomers when serving as both scavengerand alkylating activator.

Alkylalumoxanes are additionally suitable as catalyst activators,particularly for those metallocenes having halide ligands. An alumoxaneuseful as a catalyst activator typically is an oligomeric aluminumcompound represented by the general formula (R—Al—O)_(n), which is acyclic compound, or R(R—Al—O)_(n)AlR₂, which is a linear compound. Inthese formulae, each R or R₂ is a C₁ to C₅ alkyl radical, for example,methyl, ethyl, propyl, butyl or pentyl, and “n” is an integer from 1 toabout 50. Most preferably, R is methyl and “n” is at least 4, i.e.,methylalumoxane (MAO). Alumoxanes can be prepared by various proceduresknown in the art. For example, an aluminum alkyl may be treated withwater dissolved in an inert organic solvent, or it may be contacted witha hydrated salt, such as hydrated copper sulfate suspended in an inertorganic solvent, to yield an alumoxane. Generally, however prepared, thereaction of an aluminum alkyl with a limited amount of water yields amixture of the linear and cyclic species of the alumoxane.

Preferably, a scavenging compound is also used. The term “scavengingcompound” as used herein refers to those compounds effective forremoving polar impurities from the reaction solvent. Such impurities canbe inadvertently introduced with any of the polymerization reactioncomponents, particularly with solvent, monomer and comonomer feed, andadversely affect catalyst activity and stability by decreasing or eveneliminating catalytic activity, particularly when a metallocenecation-noncoordinating anion pair is the catalyst system. The polarimpurities, or catalyst poisons, include water, oxygen, oxygenatedhydrocarbons, metal impurities, etc. Preferably, steps are taken beforeprovision of such into the reaction vessel, for example, by chemicaltreatment or careful separation techniques after or during the synthesisor preparation of the various components, but some minor amounts ofscavenging compound will still normally be required in thepolymerization process itself. Typically, the scavenging compound willbe an organometallic compound such as the Group-13 organometalliccompounds of U.S. Pat. Nos. 5,153,157 and 5,241,025; EP-A-0 426 638;WO-A-91/09882; WO-A-94/03506; and WO-A-93/14132. Exemplary compoundsinclude triethyl aluminum, triethyl borane, tri-isobutyl aluminum,isobutyl aluminumoxane, those having bulky substituents covalently boundto the metal or metalloid center being preferred to minimize adverseinteraction with the active catalyst.

The catalyst system is preferably supported on a carrier, typically aninorganic oxide or chloride or a resinous material such as polyethylene.Preferably, the catalyst system includes a metallocene component withsingle or multiple cyclopentadienyl components reacted with either ametal alkyl or alkoxy component or an ionic compound component. Thesecatalysts can include partially and/or fully activated precursorcompositions. The catalysts may be modified by prepolymerization orencapsulation. Specific metallocenes and catalyst systems useful inpracticing the invention are disclosed in WO 96/11961, and WO 96/11960.Other non-limiting examples of metallocene catalysts and catalystsystems are discussed in U.S. Pat. Nos. 4,808,561, 5,017,714, 5,055,438,5,064,802, 5,124,418, 5,153,157 and 5,324,800.

The invention VLDPEs can be made using a gas phase polymerizationprocess. As used herein, the term “gas phase polymerization” refers topolymerization of polymers from monomers in a gas fluidized bed.Generally, the VLDPEs of the present invention may be made bypolymerizing alpha-olefins in the presence of a metallocene catalystunder reactive conditions in a gas phase reactor having a fluidized bedand a fluidizing medium. In a specific embodiment, the VLDPE polymer canbe made by polymerization in a single reactor (as opposed to multiplereactors). As discussed in greater detail below, a variety of gas phasepolymerization processes may be used. For example, polymerization may beconducted in uncondensed or “dry” mode, condensed mode, or“super-condensed mode.” In a specific embodiment, the liquid in thefluidizing medium can be maintained at a level greater than 2 weightpercent based on the total weight of the fluidizing medium.

The material exiting the reactor includes a very low densitypolyethylene (VLDPE), having a density from 0.890 to 0.915 g/cm³, morepreferably a density from 0.910 to 0.915 g/cm³, and a stream containingunreacted monomer gases. Following polymerization, the polymer isrecovered. In certain embodiments, the stream can be compressed andcooled, and mixed with feed components, whereupon a gas phase and aliquid phase are then returned to the reactor.

In a preferred aspect, the invention VLDPEs are copolymers, made fromethylene monomers together with at least one comonomer, e.g., hexene oroctene. Polymers having more than two types of monomers, such asterpolymers, are also included within the term “copolymer” as usedherein. For example, VLDPE terpolymers may be made, using ethylenemonomer together with any two of butene, hexene and octene. For oneembodiment of the VLDPE polymer comprising an ethylene/butene copolymer,the molar ratio of butene to ethylene should be from about 0.015 to0.035, preferably from 0.020 to 0.030. For one embodiment of the VLDPEpolymer comprising an ethylene/hexene copolymer, the molar ratio ofhexene to ethylene should be from about 0.015 to 0.035, preferably from0.020 to 0.030. For one embodiment of the VLDPE polymer comprising anethylene/octene copolymer, the molar ratio of octene to ethylene shouldbe from about 0.015 to 0.035, preferably from 0.020 to 0.030.

The comonomers that are useful in general for making VLDPE copolymersinclude α-olefins, such as C₃-C₂₀ α-olefins and preferably C₃-C₁₂α-olefins. The α-olefin comonomer can be linear or branched, and two ormore comonomers can be used, if desired. Examples of suitable comonomersinclude linear C₃-C₁₂ α-olefins, and α-olefins having one or more C₁-C₃alkyl branches, or an aryl group. Specific examples include propylene;1-butene, 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentenewith one or more methyl, ethyl or propyl substituents; 1-hexene with oneor more methyl, ethyl or propyl substituents; 1-heptene with one or moremethyl, ethyl or propyl substituents; 1-octene with one or more methyl,ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl orpropyl substituents; ethyl, methyl or dimethyl-substituted 1-decene;1-dodecene; and styrene. It should be appreciated that the list ofcomonomers above is merely exemplary, and is not intended to belimiting. Preferred comonomers include propylene, 1-butene, 1-pentene,4-methyl-1-pentene, 1-hexene, 1-octene and styrene, more preferably1-butene, 1-hexene, and 1-octene.

Although not generally preferred, other useful comonomers include polarvinyl, conjugated and non-conjugated dienes, acetylene and aldehydemonomers, which can be included in minor amounts in terpolymercompositions. Non-conjugated dienes useful as co-monomers preferably arestraight chain, hydrocarbon di-olefins or cycloalkenyl-substitutedalkenes, having 6 to 15 carbon atoms. Suitable non-conjugated dienesinclude, for example: (a) straight chain acyclic dienes, such as1,4-hexadiene and 1,6-octadiene; (b) branched chain acyclic dienes, suchas 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene; and3,7-dimethyl-1,7-octadiene; (c) single ring alicyclic dienes, such as1,4-cyclohexadiene; 1,5-cyclo-octadiene and 1,7-cyclododecadiene; (d)multi-ring alicyclic fused and bridged ring dienes, such astetrahydroindene; norbornadiene; methyl-tetrahydroindene;dicyclopentadiene (DCPD); bicyclo-(2.2.1)-hepta-2,5-diene; alkenyl,alkylidene, cycloalkenyl and cycloalkylidene norbornenes, such as5-methylene-2-norbornene (MNB), 5-propenyl-2-norbornene,5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-norbornene,5-cyclohexylidene-2-norbornene, and 5-vinyl-2-norbornene (VNB); and (e)cycloalkenyl-substituted alkenes, such as vinyl cyclohexene, allylcyclohexene, vinyl cyclooctene, 4-vinyl cyclohexene, allyl cyclodecene,and vinyl cyclododecene. Of the non-conjugated dienes typically used,the preferred dienes are dicyclopentadiene, 1,4-hexadiene,5-methylene-2-norbornene, 5-ethylidene-2-norbornene, andtetracyclo-(Δ-11,12)-5,8-dodecene. Particularly preferred diolefins are5-ethylidene-2-norbornene (ENB), 1,4-hexadiene, dicyclopentadiene(DCPD), norbornadiene, and 5-vinyl-2-norbornene (VNB). Note thatthroughout this description the terms “non-conjugated diene” and “diene”are used interchangeably.

It should be appreciated that the amount of comonomer used will dependupon the desired density of the VLDPE polymer and the specificcomonomers selected. In general, the comonomer may be present in anamount of 25% or less by weight, preferably 20% or less by weight andmore preferably 15% or less by weight. In one embodiment, the comonomermay be present in an amount of 5% or more by weight. For a givencomonomer, the density of the VLDPE polymer produced therefrom decreasesas the comonomer content increases. One skilled in the art can readilydetermine the appropriate comonomer content appropriate to produce aVLDPE polymer having a desired density.

Generally, in carrying out the gas phase polymerization processesdescribed herein, the reactor temperature can be in the range of 50° C.to 110° C., sometimes higher. However, the reactor temperature shouldnot exceed the melting point of the VLDPE being formed. A typicalreactor temperature is 80° C. The reactor pressure should be 100 to 1000psig (689 kPa to 6,895 kPa), preferably 150 to 600 psig (1034 to 4137kPa), more preferably 200 to 500 psig (1379 to 3448 kPa) and mostpreferably 250 to 400 psig (1723 to 2758 kPa).

Preferably, the process is operated in a continuous cycle. A specific,non-limiting embodiment of the gas phase polymerization process that isoperated in a continuous cycle will now be described, it beingunderstood that other forms of gas polymerization may also be used.

A gaseous stream containing one or more monomers is continuously passedthrough a fluidized bed under reactive conditions in the presence of ametallocene catalyst. This gaseous stream is withdrawn from thefluidized bed and recycled back into the reactor. Simultaneously,polymer product may be withdrawn from the reactor and new monomer ormonomers are added to replace the reacted monomer(s). In one part of thecycle, in a reactor, a cycling gas stream is heated by the heat ofpolymerization. This heat is removed in another part of the cycle by acooling system external to the reactor. Heat generated by the reactionmay be removed in order to maintain the temperature of the gaseousstream inside the reactor at a temperature below the polymer andcatalyst degradation temperatures. Further, it is often desirable toprevent agglomeration or formation of chunks of polymer that cannot beremoved as product. This may be accomplished in a variety of ways knownin the art, such as, for example, through control of the temperature ofthe gaseous stream in the reaction bed to a temperature below the fusionor sticking temperature of the polymer particles produced during thepolymerization reaction.

Heat should be removed, since the amount of polymer produced in thefluidized bed polymerization process is generally related to the amountof heat that can be withdrawn from a reaction zone in a fluidized bedwithin the reactor. During the gas phase polymerization process, heatcan be removed from the gaseous recycle stream by cooling the streamoutside the reactor. The velocity of the gaseous recycle stream in afluidized bed process should be sufficient to maintain the fluidized bedin a fluidized state. In certain conventional fluidized bed reactors,the amount of fluid circulated to remove the heat of polymerization isoften greater than the amount of fluid required for support of thefluidized bed and for adequate mixing of the solids in the fluidizedbed. However, to prevent excessive entrainment of solids in a gaseousstream withdrawn from the fluidized bed, the velocity of the gaseousstream should be regulated.

The recycle stream can be cooled to a temperature below the dew point,resulting in condensing a portion of the recycle stream, as described inU.S. Pat. Nos. 4,543,399 and 4,588,790. As set forth in those patents,the resulting stream containing entrained liquid should be returned tothe reactor without the aforementioned agglomeration and/or pluggingthat may occur when a liquid is introduced during the fluidized bedpolymerization process. For purposes of this patent, this intentionalintroduction of a liquid into a recycle stream or reactor during theprocess is referred to generally as a “condensed mode” operation of thegas phase polymerization process. As taught by the above mentionedpatents, when a recycle stream temperature is lowered to a point belowits dew point in condensed mode operation, an increase in polymerproduction is possible, as compared to production in a “non-condensing”or “dry” mode, because of increased cooling capacity. Also, asubstantial increase in space time yield, the amount of polymerproduction in a given reactor volume, can be achieved by operating incondensed mode with little or no change in product properties. Also, incertain condensed mode operations, the liquid phase of the two-phasegas/liquid recycle stream mixture remains entrained or suspended in thegas phase of the mixture. The cooling of the recycle stream to producethis two-phase mixture results in a liquid/vapor equilibrium.Vaporization of the liquid occurs when heat is added or pressure isreduced. The increase in space time yields are the result of thisincreased cooling capacity of the recycle stream which, in turn, is dueboth to the greater temperature differential between the enteringrecycle stream and the fluidized bed temperature and to the vaporizationof condensed liquid entrained in the recycle stream. In a specificnon-limiting embodiment of the process described herein, a condensedmode of operation is utilized.

In operating the gas phase polymerization process to obtain the VLDPEsof this invention, the amount of polymer and catalyst, the operatingtemperature of the reactor, the ratio of comonomer(s) to monomer and theratio of hydrogen to monomer should be determined in advance, so thatthe desired density and melt index can be achieved.

Although a variety of gas polymerization processes may be used to makethe polyolefins of the present inventions, including non-condensed ordry mode, it is preferred to use any one of a variety of condensed modeprocesses, including the condensed mode processes described in the abovepatents, as well as improved condensed mode gas polymerizationprocesses, such as those disclosed in U.S. Pat. Nos. 5,462,999, and5,405,922. Other types of condensed mode processes are also applicable,including so-called “supercondensed mode” processes, as discussed inU.S. Pat. Nos. 5,352,749 and 5,436,304.

The condensable fluids that can be used in one of the condensed mode gasphase polymerization operations may include saturated or unsaturatedhydrocarbons. Examples of suitable inert condensable fluids are readilyvolatile liquid hydrocarbons, which may be selected from saturatedhydrocarbons containing from 2 to 8 carbon atoms. Some suitablesaturated hydrocarbons are propane, n-butane, isobutane, n-pentane,isopentane, neopentane, n-hexane, isohexane, and other saturated C₆hydrocarbons, n-heptane, n-octane and other saturated C₇ and C₈hydrocarbons, or mixtures thereof. The preferred inert condensablehydrocarbons are C₄ and C₆ saturated hydrocarbons. The condensablefluids may also include polymerizable condensable comonomers such asolefins, alpha-olefins, diolefins, diolefins containing at least onealpha-olefin or mixtures thereof including some of the aforementionedmonomers which may be partially or entirely incorporated into thepolymer product.

The density of the polyethylene having the improved properties of thisinvention ranges from 0.890 to 0.915 g/cm³, preferably from 0.910 to0.915 g/cm³, more preferably from 0.911 to 0.913 g/cm³. Preferably, thepolymers have a melt index (MI) ranging from 0.01 to 20.0, preferably0.5 to 15.0. Melt index is measured according to ASTM-1238 condition E.

The preferred gas-phase, metallocene VLDPE polymers can be furthercharacterized by a narrow composition distribution. As is well known tothose skilled in the art, the composition distribution of a copolymerrelates to the uniformity of distribution of comonomer among themolecules of the polymer. Metallocene catalysts are known to incorporatecomonomer very evenly among the polymer molecules they produce. Thus,copolymers produced from a catalyst system having a single metallocenecomponent have a very narrow composition distribution, in that most ofthe polymer molecules will have roughly the same comonomer content, andwithin each molecule the comonomer will be randomly distributed. Bycontrast, conventional Ziegler-Natta catalysts generally yieldcopolymers having a considerably broader composition distribution, withcomonomer inclusion varying widely among the polymer molecules.

A measure of composition distribution is the “Composition DistributionBreadth Index” (“CDBI”). The definition of Composition DistributionBreadth Index (CDBI), and the method of determining CDBI, can be foundin U.S. Pat. No. 5,206,075 and PCT publication WO 93/03093. From theweight fraction versus composition distribution curve, the CDBI isdetermined by establishing the weight percentage of a sample that has acomonomer content within 50% of the median comonomer content on eachside of the median. The CDBI of a copolymer is readily determinedutilizing well known techniques for isolating individual fractions of asample of the copolymer. One such technique is Temperature RisingElution Fractionation (TREF) as described in Wild, et al., J. Poly.Sci., Poly. Phys. Ed., vol. 20, p. 441 (1982).

To determine CDBI, a solubility distribution curve is first generatedfor the copolymer. This may be accomplished using data acquired from theTREF technique described above. This solubility distribution curve is aplot of the weight fraction of the copolymer that is solubilized as afunction of temperature. This is converted to a weight fraction versuscomposition distribution curve. For the purpose of simplifying thecorrelation of composition with elution temperature, all fractions areassumed to have a Mn≧15,000, where Mn is the number average molecularweight of the fraction. Any low weight fractions present generallyrepresent a trivial portion of the VLDPE polymers. The remainder of thisdescription and the appended claims maintain this convention of assumingall fractions have Mn≧15,000 in the CDBI measurement.

The VLDPE polymers can also be characterized by molecular weightdistribution (MWD). Molecular weight distribution (MWD) is a measure ofthe range of molecular weights within a given polymer sample. It is wellknown that the breadth of the MWD can be characterized by the ratios ofvarious molecular weight averages, such as the ratio of the weightaverage molecular weight to the number average molecular weight, Mw/Mn,or the ratio of the Z-average molecular weight to the weight averagemolecular weight, Mz/Mw.

Mz, Mw and Mn can be measured using gel permeation chromatography (GPC),also known as size exclusion chromatography (SEC). This techniqueutilizes an instrument containing columns packed with porous beads, anelution solvent, and detector in order to separate polymer molecules ofdifferent sizes. In a typical measurement, the GPC instrument used is aWaters chromatograph equipped with ultrastyro gel columns operated at145° C. The elution solvent used is trichlorobenzene. The columns arecalibrated using sixteen polystyrene standards of precisely knownmolecular weights. A correlation of polystyrene retention volumeobtained from the standards, to the retention volume of the polymertested yields the polymer molecular weight.

Average molecular weights M can be computed from the expression:$M = \frac{\sum\limits_{i}{N_{i}M_{i}^{n + 1}}}{\sum\limits_{i}{N_{i}M_{i}^{n}}}$

where N_(i) is the number of molecules having a molecular weight M_(i).When n=0, M is the number average molecular weight Mn. When n=1, M isthe weight average molecular weight Mw. When n=2, M is the Z-averagemolecular weight Mz. The desired MWD function (e.g., Mw/Mn or Mz/Mw) isthe ratio of the corresponding M values. Measurement of M and MWD iswell known in the art and is discussed in more detail in, for example,Slade, P. E. Ed., Polymer Molecular Weights Part II, Marcel Dekker,Inc., NY, (1975) 287-368; Rodriguez, F., Principles of Polymer Systems3rd ed., Hemisphere Pub. Corp., N.Y., (1989) 155-160; U.S. Pat. No.4,540,753; Verstrate et al., Macromolecules, vol. 21, (1988) 3360; andreferences cited therein.

The VLDPE polymers recited in the claims below are preferably linearpolymers, i.e., without long chain branching. As used in the presentdisclosure, the term “linear” is applied to a polymer that has a linearbackbone and does not have long chain branching; i.e., a “linear”polymer is one that does not have the long chain branches characteristicof a SLEP polymer as defined in U.S. Pat. Nos. 5,272,236 and 5,278,272.Thus, a “substantially linear” polymer as disclosed in those patents isnot a “linear” polymer because of the presence of long chain branching.

Preferred VLDPE polymers have one or more of the followingcharacteristics, in addition to the density, melt index, and otherparameters described herein:

(a) a composition distribution CDBI of 50 to 85%, alternatively 60 to80%, or 55 to 75%, or 55% or more to 70% or less;

(b) a molecular weight distribution MWD of 2 to 3, alternatively 2.2 to2.8;

(c) a molecular weight distribution Mz/Mw of less than 2; and

(d) the presence of two peaks in a TREF measurement.

Particularly preferred VLDPEs having some or all of thesecharacteristics are the gas phase metallocene-produced VLDPEs describedabove.

Two peaks in the TREF measurement as used in this specification and theappended claims means the presence of two distinct normalized ELS(evaporation mass light scattering) response peaks in a graph ofnormalized ELS response (vertical or y axis) versus elution temperature(horizontal or x axis with temperature increasing from left to right)using the TREF method disclosed in the EXAMPLES section below. A “peak”in this context means where the general slope of the graph changes frompositive to negative with increasing temperature. Between the two peaksis a local minimum in which the general slope of the graph changes fromnegative to positive with increasing temperature. “General trend” of thegraph is intended to exclude the multiple local minimums and maximumsthat can occur in intervals of 2° C. or less. Preferably, the twodistinct peaks are at least 3° C. apart, more preferably at least 4° C.apart, even more preferably at least 5° C. apart. Additionally, both ofthe distinct peaks occur at a temperature on the graph above 20° C. andbelow 120° C. where the elution temperature is run to 0° C. or lower.This limitation avoids confusion with the apparent peak on the graph atlow temperature caused by material that remains soluble at the lowestelution temperature. Two peaks on such a graph indicates a bi-modalcomposition distribution (CD). Bimodal CD may also be determined byother methods known to those skilled in the art. One such alternatemethod for TREF measurement than can be used if the above method doesnot show two peaks is disclosed in B. Monrabal, “CrystallizationAnalysis Fractionation: A New Technique for the Analysis of BranchingDistribution in Polyolefins,” Journal of Applied Polymer Science, Vol.52, 491-499 (1994).

A preferred balance of properties, particularly in film applications,according to the invention is achieved when the long chain branching ofthe VLDPE is reduced. Therefore, with respect to the catalyst structuresdescribed above, bis-Cp structures are preferred over mono-Cpstructures, unbridged structures are preferred over bridged structures,and unbridged bis-Cp structures are the most preferred. Preferredcatalyst systems which will minimize or eliminate long chain branchingto produce polymers substantially free of or free of long chainbranching are based on un-bridged bis-Cp zirconocenes, such as but notlimited to bis (1-methyl-3-n-butyl cyclopentadiane) zirconiumdichloride.

Symmetric metallocenes may be used to produce a VLDPE polymer of thepresent invention. Symmetric metallocenes include, but are not limitedto, bis(methylcyclopentadienyl)zirconium dichloride,bis(1,3-dimethylcyclopentadienyl)zirconium dichloride,bis(1,2-dimethylcyclopentadienyl)zirconium dichloride,bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride,bis(1,2,3-trimethylcyclopentadienyl)zirconium dichloride,bis(tetramethylcyclopentadienyl)zirconium dichloride,bis(pentamethylcyclopentadienyl)zirconium dichloride,bis(ethylcyclopentadienyl)zirconium dichloride,bis(propylcyclopentadienyl)zirconium dichloride,bis(butylcyclopentadienyl)zirconium dichloride,bis(isobutylcyclopentadienyl)zirconium dichloride,bis(pentylcyclopentadienyl)zirconium dichloride,bis(isopentylcyclopentadienyl)zirconium dichloride,bis(cyclopentylcyclopentadienyl)zirconium dichloride,bis(phenylcyclopentadienyl)zirconium dichloride,bis(benzylcyclopentadienyl)zirconium dichloride,bis(trimethylsilylmethylcyclopentadienyl)zirconium dichloride,bis(cyclopropylmethylcyclopentadienyl)zirconium dichloride,bis(cyclopentylmethylcyclopentadienyl)zirconium dichloride,bis(cyclohexylmethylcyclopentadienyl)zirconium dichloride,bis(propenylcyclopentadienyl)zirconium dichloride,bis(butenylcyclopentadienyl)zirconium dichloride,bis(1,3-ethylmethylcyclopentadienyl)zirconium dichloride,bis(1,3-propylmethylcyclopentadienyl)zirconium dichloride,bis(1,3-butylmethylcyclopentadienyl)zirconium dichloride,bis(1,3-isopropylmethylcyclopentadienyl)zirconium dichloride,bis(1,3-isobutylmethylcyclopentadienyl)zirconium dichloride,bis(1,3-methylcyclopentylcyclopentadienyl)zirconium dichloride, andbis(1,2,4-dimethylpropylcyclopentadienyl)zirconium dichloride.

Unsymmetric metallocenes may be used to produce a VLDPE polymer of thepresent invention. Unsymmetric metallocenes include, but are not limitedto, cyclopentadienyl(1,3-dimethylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(1,2,4-trimethylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(tetramethylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(pentamethylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(propylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(butylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(pentylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(isobutylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(cyclopentylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(isopentylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(benzylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(phenylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(1,3-propylmethylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(1,3-butylmethylcyclopentadienyl)zirconium dichloride,cyclopentadienyl(1,3-isobutylmethylcyclopentadienyl)zirconiumdichloride,cyclopentadienyl(1,2,4-dimethylpropylcyclopentadienyl)zirconiumdichloride,(tetramethylcyclopentadienyl)(methylcyclopentadienyl)zirconiumdichloride,(tetramethylcyclopentadienyl)(1,3-dimethylcyclopentadienyl)zirconiumdichloride,(tetramethylcyclopentadienyl)(1,2,4-trimethylcyclopentadienyl)zirconiumdichloride,(tetramethylcyclopentadienyl)(propylcyclopentadienyl)zirconiumdichloride,(tetramethylcyclopentadienyl)(cyclopentylcyclopentadienyl)zirconiumdichloride,(pentamethylcyclopentadienyl)(methylcyclopentadienyl)zirconiumdichloride,(pentamethylcyclopentadienyl)(1,3-dimethylcyclopentadienyl)zirconiumdichloride,(pentamethylcyclopentadienyl)(>1,2,4-trimethylcyclopentadienyl)zirconiumdichloride,(pentamethylcyclopentadienyl)(propylcyclopentadienyl)zirconiumdichloride,(pentamethylcyclopentadienyl)(cyclopentylcyclopentadienyl)zirconiumdichloride, cyclopentadienyl(ethyltetramentylcyclopentadienyl)zirconiumdichloride, cyclopentadienyl(propyltetramentylcyclopentadienyl)zirconiumdichloride,(methylcyclopentadienyl)(propyltetramentylcyclopentadienyl)zirconiumdichloride,(1,3-dimethylcyclopentadienyl)(propyltetramentylcyclopentadienyl)zirconiumdichloride,(1,2,4-trimethylcyclopentadienyl)(propyltetramentylcyclopentadienyl)zirconiumdichloride,(propylcyclopentadienyl)(propyltetramentylcyclopentadienyl)zirconiumdichloride, cyclopentadienyl(indenyl)zirconium dichloride,(methylcyclopentadienyl)(indenyl)zirconium dichloride,(1,3-dimethylcyclopentadienyl)(indenyl)zirconium dichloride,(1,2,4-trimethylcyclopentadienyl)(indenyl)zirconium dichloride,(tetramethylcyclopentadienyl)(indenyl)zirconium dichloride,(pentamethylcyclopentadienyl)(indenyl)zirconium dichloride,cyclopentadienyl(1-methylindenyl)zirconium dichloride,cyclopentadienyl(1,3-dimethylindenyl)zirconium dichloride,cyclopentadienyl(1,2,3-trimethylindenyl)zirconium dichloride,cyclopentadienyl(4,7-dimethylindenyl)zirconium dichloride,(tetramethylcyclopentadienyl)(4,7-dimethylindenyl)zirconium dichloride,(pentamethylcyclopentadienyl)(4,7-dimethylindenyl)zirconium dichloride,cyclopentadienyl(5,6-dimethylindenyl)zirconium dichloride,(pentamethylcyclopentadienyl)(5,6-dimethylindenyl)zirconium dichloride,and (tetramethylcyclopentadienyl)(5,6-dimethylindenyl)zirconiumdichloride.

The preferred method for producing the catalyst of the invention isdescribed below and can be found in U.S. application Ser. No. 265,533,filed Jun. 24, 1994, now abandoned, and Ser. No. 265,532, filed Jun. 24,1994, now abandoned, both are hereto fully incorporated by reference intheir entirety. In a preferred embodiment, the metallocene catalystcomponent is typically slurried in a liquid to form a metallocenesolution and a separate solution is formed containing an activator and aliquid. The liquid can be any compatible solvent or other liquid capableof forming a solution or the like with at least one metallocene catalystcomponent and/or at least one activator. In the preferred embodiment theliquid is a cyclic aliphatic or aromatic hydrocarbon, most preferablytoluene. The metallocene and activator solutions are preferably mixedtogether and added to a porous support such that the total volume of themetallocene solution and the activator solution or the metallocene andactivator solution is less than four times the pore volume of the poroussupport, more preferably less than three times, even more preferablyless than two times, and more preferably in the 1-1.5 times to 2.5-4times range and most preferably in the 1.5 to 3 times range. Also, inthe preferred embodiment, an antistatic agent is added to the catalystpreparation.

In one embodiment, the metallocene catalyst is prepared from silicadehydrated at 600° C. The catalyst is a commercial scale catalystprepared in a mixing vessel with and agitator. An initial charge of 1156pounds (462 Kg) toluene is added to the mixer. This was followed bymixing 925 pounds (421 Kg) of 30 percent by weight methyl aluminoxane intoluene. This is followed with 100 pounds (46 Kg) of 20 percent byweight bis(1,3-methyl-n-butyl cyclopentadienyl) zirconium dichloride intoluene (20.4 pounds (9.3 Kg) of contained metallocene). An additional144 pounds (66 Kg) of toluene is added to the mixer to rinse themetallocene feed cylinder and allowed to mix for 30 minutes at ambientconditions. This is followed by 54.3 pounds (25 Kg) of an AS-990 intoluene, surface modifier solution, containing 5.3 pounds (2.4 Kg) ofcontained AS-990. An additional 100 pounds (46 Kg) of toluene rinsed thesurface modifier container and was added to the mixer. The resultingslurry is vacuum dried at 3.2 psia (70.6 kPa) at 175° F. (79° C.) to afree flowing powder. The final catalyst weight was 1093 pounds (497 Kg).The catalyst can have a final zirconium loading of 0.40% and an aluminumloading of 12.0%.

In one preferred embodiment a substantially homogenous catalyst systemis preferred. For the purposes of this patent specification and appendedclaims, a “substantially homogenous catalyst” is one in which the moleratio of the transition metal of the catalyst component, preferably withan activator, is evenly distributed throughout a porous support.

The procedure for measuring the total pore volume of a porous support iswell known in the art. Details of one of these procedures is discussedin Volume 1, Experimental Methods in Catalytic Research (Academic Press,1968) (specifically see pages 67-96). This preferred procedure involvesthe use of a classical BET apparatus for nitrogen absorption. Anothermethod well know in the art is described in Innes, Total porosity andParticle Density of Fluid Catalysts By Liquid Titration, Vol. 28, No. 3,Analytical Chemistry 332-334 (March, 1956).

The mole ratio of the metal of the activator component to the transitionmetal of the metallocene component is in the range of ratios between0.3:1 to 1000:1, preferably 20:1 to 800:1, and most preferably 50:1 to500:1. Where the activator is an ionizing activator as previouslydescribed the mole ratio of the metal of the activator component to thetransition metal component is preferably in the range of ratios between0.3:1 to 3:1. component to the transition metal component is preferablyin the range of ratios between 0.3:1 to 3:1.

Typically in a gas phase polymerization process a continuous cycle isemployed where in one part of the cycle of a reactor, a cycling gasstream, otherwise known as a recycle stream or fluidizing medium, isheated in the reactor by the heat of polymerization. This heat isremoved in another part of the cycle by a cooling system external to thereactor. (See for example U.S. Pat. Nos. 4,543,399, 4,588,790,5,028,670, 5,352,749, 5,405,922, 5,436,304, 5,453,471 and 5,462,999 allof which are fully incorporated herein by reference.)

Generally in a gas fluidized bed process for producing polymer frommonomers a gaseous stream containing one or more monomers iscontinuously cycled through a fluidized bed in the presence of acatalyst under reactive conditions. The gaseous stream is withdrawn fromthe fluidized bed and recycled back into the reactor. Simultaneously,polymer product is withdrawn from the reactor and new or fresh monomeris added to replace the polymerized monomer.

In one embodiment of the process of the invention the process isessentially free of a scavenger. For the purposes of this patentspecification and appended claims the term “essentially free” means thatduring the process of the invention no more than 10 ppm of a scavengerbased on the total weight of the recycle stream is present at any givenpoint in time during the process of the invention.

In another embodiment of the process of the invention the process issubstantially free of a scavenger. For the purposes of this patentspecification and appended claims the term “substantially free” isdefined to be that during the process of the invention no more than 50ppm of a scavenger based on the total weight of a fluidized bed ispresent at any given point in time during the process of the invention.

In one embodiment during reactor start-up to remove impurities andensure polymerization is initiated, a scavenger is present in an amountless than 300 ppm, preferably less than 250 ppm, more preferably lessthan 200 ppm, even more preferably less than 150 ppm, still morepreferably less than 100 ppm, and most preferably less than 50 ppm basedon the total bed weight of a fluidized bed during the first 12 hoursfrom the time the catalyst is placed into the reactor, preferably up to6 hours, more preferably less than 3 hours, even more preferably lessthan 2 hours, and most preferably less than 1 hour and then theintroduction of the scavenger is halted.

In another embodiment of the process of the invention the scavenger ispresent in an amount sufficient until the catalyst of the invention hasachieved a catalyst productivity on a weight ratio basis of greater than1000 grams of polymer per gram of the catalyst, preferably greater thanabout 1500, more preferably greater than 2000, even more preferablygreater than 2500, and most preferably greater than 3000.

In another embodiment of the process of the invention during start-upthe scavenger is present in an amount sufficient until the catalyst ofthe invention has achieved a catalyst productivity 40 percent of that ofsteady-state, preferably less than 30 percent, even more preferably lessthan 20 percent and most preferably less than 10 percent. For thepurposes of this patent specification and appended claims “steady state”is the production rate, weight of polymer being produced per hour.

The productivity of the catalyst or catalyst system is influenced by themain monomer, (i.e., ethylene or propylene) partial pressure. Thepreferred mole percent of the monomer, ethylene or propylene, is fromabout 25 to 90 mole percent and the monomer partial pressure is in therange of from about 75 psia (517 kPa) to about 300 psia (2069 kPa),which are typical conditions in a gas phase polymerization process.

When a scavenger is utilized in the process of the invention thescavenger can be introduced typically into the reactor directly orindirectly into the recycle stream or into any external means capable ofintroducing the scavenger into the reactor. Preferably the scavengerenters into the reactor directly, and most preferably directly into thereactor bed or below the distributor plate in a typical gas phaseprocess, preferably after the bed is in a fluidized state. In oneembodiment the scavenger can be introduced once, intermittently orcontinuously to the reactor system.

The scavenger used in the process of the invention is introduced to thereactor at a rate equivalent to 10 ppm to 100 ppm based on the steadystate, production rate, and then scavenger introduction is stopped.

In yet another embodiment particularly during start-up the scavengerwhen used is introduced at a rate sufficient to provide an increase incatalyst productivity on a weight ratio basis of a rate of 200 grams ofpolymer per gram of catalyst per minute, preferably at a rate of 300,even more preferably at a rate of 400 and most preferably at a rate of500.

In another embodiment, the mole ratio of the metal of the scavenger tothe transition metal of the metallocene catalyst component equals about,about 0.2 multiplied by the ppm of a scavenger based on the productionrate multiplied by the catalyst productivity in kilograms of polymer pergram of catalyst. The range of the mole ratio is from about 300 to 10.In a preferred embodiment, where an alkyl aluminum is used as thescavenger the mole ratio is represented as aluminum (Al) to transitionmetal, for example, zirconium, where the moles of. Al are based on thetotal amount of scavenger used.

It is also preferred that hydrogen not be added to the systemsimultaneously with the scavenger. It is also within the scope of thisinvention that the scavenger can be introduced on a carrier separatefrom that used when a supported metallocene catalyst system is used inthe process of the invention.

Fines for the purpose of this patent specification and appended claimsare polymer particles less than 125 mu in size. Fines of this size canbe measured by using a standard 120 mesh unit sieve screen. In apreferred embodiment the amount of scavenger present in the reactor atany given point in time during the process of the invention the level offines less than 125 mu is less than 10%, preferably less than 1%, morepreferably less than 0.85% to less than 0.05%.

It is within the scope of the invention that a system external to thereactor for removing scavengers introduced in the process of theinvention from the recycle stream may be used. This would then preventthe recycle of the scavenger back into the reactor and prevent scavengerbuild-up in the reactor system. It is preferred that such a system isplaced prior to the heat exchanger or compressor in the recycle streamline. It is contemplated that such a system would condense the scavengerout of the fluidizing medium in the recycle stream line. It would bepreferred that the fluidizing medium is treated to remove the scavenger,see for example U.S. Pat. No. 4,460,755, incorporated herein byreference.

It is also contemplated by the process of the invention that scavengercan be intermittently introduced during the process wherein greater than90%, preferably greater than 95% of all the scavenger introduced isremoved from the recycle stream.

It is also contemplated by this invention that the catalyst or catalystsystem or components thereof of the invention can be used upon start-upas a scavenger, however, this would be an expensive procedure.

In the most preferred embodiment of the invention the process is a gasphase polymerization process operating in a condensed mode. For thepurposes of this patent specification and appended claims the process ofpurposefully introducing a recycle stream having a liquid and a gasphase into a reactor such that the weight percent of liquid based on thetotal weight of the recycle stream is greater than about 2.0 weightpercent is defined to be operating a gas phase polymerization process ina “condensed mode”.

In one embodiment of the process of the invention the weight percent ofliquid in the recycle stream based on the total weight of the recyclestream is in the range of about 2 to about 50 weight percent, preferablygreater than 10 weight percent and more preferably greater than 15weight percent and even more preferably greater than 20 weight percentand most preferably in the range between about 20 and about 40 percent.However, any level of condensed can be used depending on the desiredproduction rate.

In another embodiment of the process of the invention the amount ofscavenger utilized if any is used should be in a mole ratio less than100, preferably less than 50, more preferably less than about 25 basedon the mole ratio of the metal of the transition metal scavenger to thetransition metal of the metallocene where the scavenger is an aluminumcontaining organometallic compound and the transition metal of themetallocene is a Group 4 metal then the mole ratio above is based on themoles of aluminum to the moles of the Group 4 metal of the catalyst.

Fouling is a term used to describe the collection of polymer deposits onsurfaces in a reactor. Fouling is detrimental to all parts of apolymerization process, including the reactor and its associatedsystems, hardware, etc. Fouling is especially disruptive in areasrestricting gas flow or liquid flow. The two major areas of primaryconcern are the heat exchanger and distributor plate fouling. The heatexchanger consists of a series of small diameter tubes arranged in atube bundle. The distributor plate is a solid plate containing numeroussmall diameter orifices through which the gas contained in a recyclestream is passed through before entering the reaction zone ordistributed into a bed of solid polymer in a fluidized bed reactor suchas described in U.S. Pat. No. 4,933,149, incorporated herein byreference.

Fouling manifests itself as an increase in the pressure drop acrosseither the plate, cooler, or both. Once the pressure drop becomes toohigh, gas or liquid can no longer be circulated efficiently by thecompressor, and it is often necessary to shut the reactor down. Cleaningout the reactor can take several days and is very time consuming andcostly. Fouling can also occur in the recycle gas piping and compressor,but usually accompanies plate and cooler fouling.

To quantify the rate of fouling it is useful to define a fouling factor,F. F is the fraction of the area of a hole that is fouled. If F=0 (0%)then there is no fouling. Conversely, if F=1 (100%) the hole iscompletely plugged. It is possible to relate the fouling to the pressuredrop, DELTA P, at a given time in terms of the pressure drop of a cleansystem, DELTA P0. As fouling increases DELTA P increases and is largerthan the initial pressure drop, DELTA P0. F is given by the followingexpressions: [See equation in original] (I) Cooler Fouling [See OriginalPatent for Chemical Structure Diagram] (II) In general, when F isgreater than about 0.3 to about 0.4 (30-40%) a reactor shutdown isinevitable. Preferably, F is less than 40%, preferably less than 30%,even more preferably less than 20%, still more preferably less than 15%and most preferably less than 10% to 0%. The rate of fouling, the changein F as a function of time, is used to quantify fouling. If no foulingoccurs the rate of fouling is zero. A minimum acceptable rate of foulingfor a commercial operation is about 12 percent/month or 0.4 percent/day,preferably less than 0.3 percent/day, even more preferably less than 0.2percent/day and most preferably less than 0.1 percent/day.

Particle size is determined as follows; the particle size is measured bydetermining the weight of the material collected on a series of U.S.Standard sieves and determining the weight average particle size.

Fines are defined as the percentage of the total distribution passingthrough 120 mesh standard sieve.

In one embodiment, the process is operated using a metallocene catalystbased on bis(1,3-methyl-n-butyl cyclopentadienyl) zirconium dichlorideis described in this example. It shows the fouling effect of operating acommercial reactor using TEAL. This example includes information from astartup of a commercial reactor on metallocene catalyst.

Possible optimizations of the gas phase polymerization process andadditional catalyst preparations are disclosed in U.S. Pat. Nos.5,763,543, 6,087,291, and 5,712,352, and PCT published applications WO00/02930 and WO 00/02931.

Although the VLPDE polymer component of the VLDPE/LDPE blends of theinvention has been discussed as a single polymer, blends of two or moresuch VLDPE polymers, preferably two or more m-VLDPE polymers, having theproperties described herein are also contemplated.

In any of the gas phase polymerization processes described herein,including those in the patents referenced herein, the unreacted monomersin the product stream may be recycled. Preferably, to make the VLDPEs ofthe invention with the desired density, the composition of the recyclestream should be carefully controlled so that the proper ratio ofcomonomers is maintained, as discussed above.

Another aspect of the invention relates to a polymer product containingany one of the very low density polyethylenes (VLDPEs) made using a gasphase polymerization process carried out in the presence of metallocene.Such polymer products preferably contain a sufficient amount of theVLDPE to provide them with improved properties such as the toughnessproperties described above in the Summary, e.g., the above-mentionedDart Drop and/or Puncture values. Such products include a number offilm-based products, such as films made from the VLDPEs, cast films,melt-blown films, coextruded films, films made of blends of VLDPEtogether with other polymers, laminated films, extrusion coatings, filmswith high oxygen transmission rates, multilayer films containing theVLDPEs, sealing layers and cling layers that contain the VLDPEs andproducts that include such sealing layers and cling layers. The blendsof the invention have the VLDPE together with other polymers, such asLDPE, MDPE, HDPE, polypropylene and copolymers such asethylene/propylene copolymers. This invention also includes productshaving specific end-uses, particularly film-based products for which thetoughness properties are desirable, such as stretch films, shippingsacks, flexible and food packaging (e.g., fresh cut produce packaging),personal care films pouches, medical film products (such as IV bags),diaper backsheets and housewrap. Another product of this inventionincludes VLDPE that has been rendered breathable and used either alone(as a single layer film) or in combination with one or more other layersor films or fabrics, including woven or nonwoven films or fabrics. Theproducts also include extrusion coating compositions containing theVLDPE. Several specific film and coating applications are describedbelow.

4.2 The LDPE Component

The polymer blend also includes a low density polyethylene (LDPE)polymer. As used herein, the terms “low density polyethylene” polymerand “LDPE” polymer refer to a homopolymer or preferably copolymer ofethylene having a density of from 0.916 to 0.940 g/cm³. Polymers havingmore than two types of monomers, such as terpolymers, are also includedwithin the term “copolymer” as used herein. The comonomers that areuseful in general for making LDPE copolymers include α-olefins, such asC₃-C₂₀ α-olefins and preferably C₃-C₁₂ α-olefins. The α-olefin comonomercan be linear or branched, and two or more comonomers can be used, ifdesired. Examples of suitable comonomers include linear C₃-C₁₂α-olefins, and α-olefins having one or more C₁-C₃ alkyl branches, or anaryl group. Specific examples include propylene; 3-methyl-1-butene;3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl,ethyl or propyl sibstituents; 1-hexene with one or more methyl, ethyl orpropyl substituents; 1-heptene with one or more methyl, ethyl or propylsubstituents; 1-octene with one or more methyl, ethyl or propylsubstituents; 1 nonene with one or more methyl, ethyl or propylsubstituents; ethyl, methyl or dimethyl-substituted 1-decene;1-dodecene; and styrene. It should be appreciated that the list ofcomonomers above is merely exemplary, and is not intended to belimiting. Preferred comonomers include propylene, 1-butene, 1-pentene,4-methyl-1-pentene, 1-hexene, 1-octene and styrene.

Other useful comonomers include polar vinyl, conjugated andnon-conjugated dienes, acetylene and aldehyde monomers, which can beincluded in minor amounts in terpolymer compositions. Non-conjugateddienes useful as co-monomers preferably are straight chain, hydrocarbondi-olefins or cycloalkenyl-substituted alkenes, having 6 to 15 carbonatoms. Suitable non-conjugated dienes include, for example: (a) straightchain acyclic dienes, such as 1,4-hexadiene and 1,6-octadiene; (b)branched chain acyclic dienes, such as 5-methyl-1,4-hexadiene;3,7-dimethyl-1,6-octadiene; and 3,7-dimethyl-1,7-octadiene; (c) singlering alicyclic dienes, such as 1,4-cyclohexadiene; 15-cyclo-octadieneand 1,7-cyclododecadiene; (d) multi-ring alicyclic fused and bridgedring dienes, such as tetrahydroindene; norbornadiene;methyl-tetrahydroindene; dicyclopentadiene (DCPD);bicyclo-(2.2.1)-hepta-2,5-diene; alkenyl, alkylidene, cycloalkenyl andcycloalkylidene norbornenes, such as 5-methylene-2-norbornene (MNB);5—propenyl-2-norbornene, 5-isopropylidene-2-norbornene,5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, and5-vinyl-2-norbornene (VNB); and (e) cycloalkenyl-substituted alkenes,such as vinyl cyclohexene, allyl cyclohexene, vinyl cyclooctene, 4-vinylcyclohexene, allyl cyclodecene, and vinyl cyclododecene. Of thenon-conjugated dienes typically used, the preferred dienes aredicyclopentadiene, 1,4-hexadiene, 5-methylene-2-norbornene,5-ethylidene-2-norbornene, and tetracyclo-(Δ-11,12)-5,8-dodecene.Particularly preferred diolefins are 5-ethylidene-2-norbornene (ENB),1,4-hexadiene, dicyclopentadiene (DCPD), norbornadiene, and5-vinyl-2-norbornene (VNB).

The amount of comonomer used will depend upon the desired density of theLDPE polymer and the specific comonomers selected. One skilled in theart can readily determine the appropriate comonomer content appropriateto produce an LDPE polymer having a desired density.

The LDPE polymer has a density of 0.916 g/cm³ to 0.940 g/cm³, andpreferably from 0.916 g/cm³ to 0.925 g/cm³. The LDPE polymer can have amelt index of from 0.5 to 20 g/10 min (dg/min), as measured inaccordance with ASTM-1238 condition E. Alternative lower limits for themelt index include 0.7 and 1.0 g/10 min, and alternative upper limitsfor the melt index include 5, 10 and 15 g/10 min, with melt index rangesfrom any lower limit to any upper limit being within the scope of theinvention.

The LDPE polymer can be produced using any conventional polymerizationprocess and suitable catalyst, such as a Ziegler-Natta catalyst or ametallocene catalyst. Metallocene-catalyzed LDPE's (m-LDPE) arepreferred. Particularly preferred m-LDPEs are the gas-phase, metallocenecatalyzed LLPDEs described in WO 94/26816, the disclosure of which isincorporated herein by reference for purposes of U.S. patent practice.Examples of suitable LDPEs include the metallocene LDPEs commerciallyavailable under the tradename EXCEED™ from ExxonMobil Chemical Co.,Houston, Tex., the Ziegler-Natta LDPEs available as ExxonMobil LL seriesLDPEs, from ExxonMobil Chemical Co., Houston, Tex., and the DOWLEX™ LDPEresins available from Dow Chemical Co.

Although the LLPDE polymer component of the VLDPE/LDPE blends of theinvention has been discussed as a single polymer, blends of two or moresuch LDPE polymers, preferably two or more metallocene-catalyzed LDPEpolymers, having the properties described herein are also contemplated.

4.3 VLDPE-LDPE Blends

In one embodiment, the present invention provides a polymer blend, theblend including a VLDPE polymer and an LDPE polymer. The blend caninclude any of the VLDPE polymers described herein, preferably ametallocene-catalyzed VLDPE polymer, and more preferably a gas-phaseproduced metallocene catalyzed VLDPE polymer. The blend can include anyof the LDPE polymers described herein, preferably ametallocene-catalyzed LDPE polymer, and more preferably a gas-phaseproduced metallocene catalyzed LDPE polymer.

The blends can be formed using conventional equipment and methods, sucha by dry blending the individual components and subsequently melt mixingin a mixer, or by mixing the components together directly in a mixer,such as a Banbury mixer, a Haake mixer, a Brabender internal mixer, or asingle or twin-screw extruder including a compounding extruder and aside-arm extruder used directly downstream of a polymerization process.Additionally, additives can be included in the blend, in one or morecomponents of the blend, and/or in a product formed from the blend, suchas a film, as desired. Such additives are well known in the art, and caninclude, for example: fillers; antioxidants (e.g., hindered phenolicssuch as IRGANOX™ 1010 or IRGANOX™ 1076 available from Ciba-Geigy);phosphites (e.g., IRGAFOS™ 168 available from Ciba-Geigy); anti-clingadditives; tackifiers, such as polybutenes, terpene resins, aliphaticand aromatic hydrocarbon resins, alkali metal and glycerol stearates andhydrogenated rosins; UV stabilizers; heat stabilizers; antiblockingagents; release agents; anti-static agents; pigments; colorants; dyes;waxes; silica; fillers; talc and the like.

The blends include at least 1 weight percent and up to 99 weight percentof the VLDPE polymer, and at least 1 weight percent and up to 99 weightpercent of the LDPE polymer, with these weight percents based on thetotal weight of the VLDPE and LDPE polymers of the blend. Alternativelower limits of the VLDPE polymer can be 5%, 10%, 20%, 30% or 40% byweight. Alternative upper limits of the VLDPE polymer can be 95%, 90%,80%, 70%, and 60% by weight. Ranges from any lower limit to any upperlimit are within the scope of the invention. Preferred blends includefrom 5 to 85%, alternatively from 10-50% or from 10-30% by weight of theVLDPE polymer. The balance of the weight percentage is the weight of theLDPE polymer component.

In one preferred embodiment, the polymer blend includes ametallocene-catalyzed VLDPE polymer having a density of less than 0.916g/cm³, and an LDPE polymer having a density of from 0.916 to 0.940g/cm³.

In another preferred embodiment, the polymer blend includes a gas-phasemetallocene-produced VLDPE polymer, the VLDPE polymer being a copolymerof ethylene and at least one C₃ to C₁₂ alpha olefin and having a densityof from 0.900 to 0.915 g/cm³ and a melt index of from 0.5 to 20 g/10min; and a metallocene-produced LDPE polymer, the LDPE polymer being acopolymer of ethylene and at least one C₃ to C₁₂ alpha olefin and havinga density of from 0.916 to 0.925 g/cm³ and a melt index of from 0.5 to20 g/10 min, wherein the blend includes 5-85% by weight of the VLDPEpolymer and 95-15% by weight of the LDPE polymer, preferably 10-50% byweight of the VLDPE polymer and 90-50% by weight of the LDPE polymer,based on the total weight of the VLDPE and LDPE polymers.

In any of these embodiments, the VLDPE polymer, the LDPE polymer, orboth, can be blends of such polymers. I.e., the VLDPE polymer componentof the blend can itself be a blend of two or more VLDPE polymers havingthe characteristics described herein, and alternatively or additionally,the LDPE polymer component of the blend can itself be a blend of two ormore LDPE polymers having the characteristics described herein.

4.4 Films, Coatings, and Articles

Films of the metallocene VLDPE polymers of the present invention can beformed by conventional processes, preferably by a chill roll castingprocess. The polymer is extruded by an extruder, melt processed througha slot die, and melt drawn down by an optional air knife and chill roll.Extrusion coating are generally processed at higher temperatures thancast films, typically about 600° F., in order to promote adhesion of theextruded material to the substrate. The resulting polymer film iscollected on a winder. The film thickness can be monitored by a gaugemonitor, and the film can be edge trimmed by a trimmer. One or moreoptional treaters can be used to surface treat the film, if desired.Such chill roll casting processes and apparatus are well known in theart, and are described, for example, in The Wiley Encyclopedia ofPackaging Technology, Second Edition, A. L. Brody and K. S. Marsh, Ed.,John Wiley and Sons, Inc., New York (1997). Other extrusion coatingprocesses are known in the art, and are described, for example, in U.S.Pat. Nos. 5,268,230, 5,178,960 and 5,387,630.

In one embodiment, the present invention is directed to metalloceneVLDPE films or coatings of the films on flexible media such as paper,metal foil, polymeric materials such as polypropylene, polyester, andthe like. The film resins have a density less than 0.916 g/cm³, and amelt flow ratio (“MFR”) of from 6-15 dg/min, preferably of from 9-12dg/min. In general, the density of the film resin is from 0.890 to 0.915g/cm³, from 0.905 to 0.915 g/cm³, from 0.910 to 0.915 g/cm³, or from0.911 to 0.913 g/cm³. In a particular embodiment, the film resin has adensity of 0.912 g/cm³ and an MFR of 12 dg/min. These films and coatingscan be produced as described above.

It should be emphasized that the VLDPE/LDPE blends of the presentinvention can make use of VLDPE polymers produced by the methodsdescribed herein, or VLDPE polymers produced by other methods known inthe art for use in making metallocene VLDPE polymers.

In another embodiment, the present invention is directed to metalloceneVLDPE films or coatings of the films on flexible media such as paper,metal foil and the like, wherein the film or coating is formed of aresin including a metallocene VLDPE blended with an LDPE. The substratecan also be stock for milk cartons, juice containers, films, etc. Theamount of LDPE in the blend can be from 1 to 40% by weight, preferablyfrom 5 to 35%, from 10 to 30%, or from 15 to 25% by weight. In aparticular embodiment, the resin blend includes 20% by weight of an LDPEsuch as LD200 or LD270, which are commercially available LDPE resins.The resin blends and/or the mVLDPE in the blends, have a density lessthan 0.916 g/cm³, and a melt flow ratio (“MFR”) of from 6-15 dg/min,preferably of from 9-12 dg/min. These films and coatings can be producedas described above. The LDPE and mVLDPE can be blended in conventionalprocesses well known in the art.

The films and coatings of the present invention are also suitable foruse in laminate structures; i.e., with a film or a coating as describedherein disposed between two substrates. These films and coatings arealso suitable for use as heat sealing or moisture barrier layers insingle- or multi-layer structures.

Another aspect of the invention relates to the formation of monolayerfilms from the polymer blend compositions discussed above. These filmsmay be formed by any number of well known extrusion or coextrusiontechniques discussed below. Films of the invention may be unoriented,uniaxially oriented or biaxially oriented. Physical properties of thefilm may vary depending on the film forming techniques used.

Another aspect of the invention relates to the formation of multilayerfilms from the polymer blend compositions discussed above.Multiple-layer films may be formed by methods well known in the art. Thetotal thickness of multilayer films may vary based upon the applicationdesired. A total film thickness of about 5-100 μm, more typically about10-50 μm, is suitable for most applications. Those skilled in the artwill appreciate that the thickness of individual layers for multilayerfilms may be adjusted based on desired end use performance, resin orcopolymer employed, equipment capability and other factors. Thematerials forming each layer may be coextruded through a coextrusionfeedblock and die assembly to yield a film with two or more layersadhered together but differing in composition. Coextrusion can beadapted for use in both cast film or blown film processes.

When used in multilayer films, the VLDPE/LDPE polymer blend may be usedin any layer of the film, or in more than one layer of the film, asdesired. When more than one layer of the film is formed of a VLDPE/LDPEpolymer blend of the present invention, each such layer can beindividually formulated; i.e., the layers formed of the VLDPE/LDPEpolymer blend can be the same or different chemical composition,density, melt index, thickness, etc., depending upon the desiredproperties of the film.

To facilitate discussion of different film structures of the invention,the following notation is used herein. Each layer of a film is denoted“A” or “B”, where “A” indicates a conventional film layer as definedbelow, and “B” indicates a film layer formed of any of the VLDPEpolymers of the present invention. Where a film includes more than one Alayer or more than one B layer, one or more prime symbols (′, ″, ′″,etc.) are appended to the A or B symbol to indicate layers of the sametype (conventional or inventive) that can be the same or can differ inone or more properties, such as chemical composition, density, meltindex, thickness, etc. Finally, the symbols for adjacent layers areseparated by a slash (/). Using this notation, a three-layer film havingan inner layer of a VLDPE/LDPE polymer blend of the invention disposedbetween two outer, conventional film layers would be denoted A/B/A′.Similarly, a five-layer film of alternating conventional/inventivelayers would be denoted A/B/A′/B′/A″. Unless otherwise indicated, theleft-to-right or right-to-left order of layers does not matter, nor doesthe order of prime symbols; e.g., an A/B film is equivalent to a B/Afilm, and an A/A′/B/A″ film is equivalent to an A/B/A′/A″ film, forpurposes of the present invention. The relative thickness of each filmlayer is similarly denoted, with the thickness of each layer relative toa total film thickness of 100 (dimensionless) is indicated numericallyand separated by slashes; e.g., the relative thickness of an A/B/A′ filmhaving A and A′ layers of 10 μm each and a B layer of 30 μm is denotedas 20/60/20.

For the various films described herein, the “A” layer can be formed ofany material known in the art for use in multilayer films or infilm-coated products. Thus, for example, the A layer can be formed of apolyethylene homopolymer or copolymer, and the polyethylene can be, forexample, a VLDPE, a low density polyethylene (LDPE), an LLDPE, a mediumdensity polyethylene (MDPE), or a high density polyethylene (HDPE), aswell as other polyethylenes known in the art. The polyethylene can beproduced by any suitable process, including metallocene-catalyzedprocesses and Ziegler-Natta catalyzed processes. Further, the A layercan be a blend of two or more such polyethylenes, and can includeadditives known in the art. Further, one skilled in the art willunderstand that the layers of a multilayer film must have theappropriate viscosity match.

In multilayer structures, one or more A layers can also be anadhesion-promoting tie layer, such as PRIMACOR™ ethylene-acrylic acidcopolymers available from The Dow Chemical Co., and/or ethylene-vinylacetate copolymers. Other materials for A layers can be, for example,foil, nylon, ethylene-vinyl alcohol copolymers, polyvinylidene chloride,polyethylene terephthalate, oriented polypropylene, ethylene-vinylacetate copolymers, ethylene-acrylic acid copolymers,ethylene-methacrylic acid copolymers, graft modified polymers, otherpolyethylenes, such as HDPE, LDPE, LMDPE, and MDPE, and paper.

The “B” layer is formed of a VLDPE/LDPE polymer blend of the invention,and can be any of such blends described herein. In one embodiment, the Blayer is formed of a blend of a metallocene-catalyzed VLDPE polymerhaving a density of less than 0.916 g/cm³ and a LDPE polymer having adensity of from 0.916 to 0.940 g/cm³. In another embodiment, the B layeris formed of a blend comprising: (a) a gas-phase metallocene-producedVLDPE copolymer of ethylene and at least one C₃ to C₁₂ alpha olefin andhaving a density of from 0.900 to 0.915 g/cm³ and a melt index of from0.5 to 10 g/10 min; and (b) a LDPE homopolymer or copolymer having adensity of from 0.916 to 0.940 g/cm³ and a melt index of from 0.5 to 20g/10 min. In one embodiment, the B layer is formed of a blend comprisinga gas-phase metallocene-produced VLDPE having a melt index having thelower limits of 0.5 g/10 min or more, 0.7 g/10 min or more, 1 g/10 minor more and having the upper limits of 5 g/10 min or less, 3 g/10 min orless, or 2 g/10 min or less, with melt index ranges from any lower limitto any upper limit being within the scope of the invention. In onepreferred embodiment, the B layer is formed of a blend as describedherein, wherein the VLDPE component of the blend has one or more of thefollowing characteristics, in addition to the density, melt index, andother parameters described herein:

(a) a composition distribution CDBI of 50 to 85%, alternatively 60 to80%, or 55 to 75%, or 55% or more to 70% or less;

(b) a molecular weight distribution Mw/Mn of 2 to 3, alternatively 2.2to 2.8;

(c) a molecular weight distribution Mz/Mw of less than 2; and

(d) the presence of two peaks in a TREF measurement.

The thickness of each layer of the film, and of the overall film, is notparticularly limited, but is determined according to the desiredproperties of the film. Typical film layers have a thickness of about 1to 1000 μm, more typically about 5 to 100 μm, and typical films have anoverall thickness of 10 to 100 μm.

In one embodiment, the present invention provides a single-layer(monolayer) film formed of any of the VLDPE/LDPE polymer blends of theinvention; i.e., a film having a single layer which is a B layer asdescribed above.

In other embodiments, and using the nomenclature described above, thepresent invention provides multilayer films with any of the followingexemplary structures:

(a) two-layer films, such as A/B and B/B′;

(b) three-layer films, such as A/B/A′, A/A′/B, B/A/B′ and B/B′/B″;

(c) four-layer films, such as A/A′/A″/B, A/A′/B/A″, A/A′/B/B′,A/B/A′/B′, A/B/B′/A′, B/A/A′/B′, A/B/B′/B″, B/A/B′/B″ and B/B′/B″/B′″;

(d) five-layer films, such as A/A′/A″/A′″/B, A/A′/A″/B/A′″,A/A′/B/A″/A′″, A/A′/A″/B/B′, A/A′/B/A″/B′, A/A′/B/B′/A″, A/B/A′/B′/A″,A/B/A′/A″/B, B/A/A′/A″/B′, A/A′/B/B′/B″, A/B/A′/B′/B″, A/B/B′/B″/A′,B/A/A′/B′/B″, B/A/B′/A′/B″, B/A/B′/B″/A′, A/B/B′/B″/B′″, B/A/B′/B″/B′″,B/B′/A/B″/B′″, and B/B′/B″/B′″/B″″;

and similar structures for films having six, seven, eight, nine or morelayers. It should be appreciated that films having still more layers canbe formed using the VLDPE/LDPE polymer blends of the invention, and suchfilms are within the scope of the invention.

In any of the embodiments above, one or more A layers can be replacedwith a substrate layer, such as glass, plastic, paper, metal, etc., orthe entire film can be coated or laminated onto a substrate. Thus,although the discussion herein has focussed on multilayer films, thefilms of the VLDPE/LDPE polymer blends of the present invention can alsobe used in as coatings; e.g., films formed of the inventive polymers, ormultilayer films including one or more layers formed of the inventivepolymers, can be coated onto a substrate such as paper, metal, glass,plastic and other materials capable of accepting a coating. Such coatedstructures are also within the scope of the present invention.

As described below, the films can be cast films or blown films. Thefilms can further be embossed, or produced or processed according toother known film processes. The films can be tailored to specificapplications by adjusting the thickness, materials and order of thevarious layers, as well as the additives in each layer.

In one aspect, films containing the polymer blend composition, monolayeror multilayer, may be formed by using casting techniques, such as achill roll casting process. For example, a composition can be extrudedin a molten state through a flat die and then cooled to form a film. Asa specific example, cast films can be prepared using a pilot scalecommercial cast film line machine as follows. Pellets of the polymer aremelted at a temperature ranging from about 250° C. to about 300° C.,with the specific melt temperature being chosen to match the meltviscosity of the particular resins. In the case of a multilayer castfilm, the two or more different melts are conveyed to a coextrusionadapter that combines the two or more melt flows into a multilayer,coextruded structure. This layered flow is distributed through a singlemanifold film extrusion die to the desired width. The die gap opening istypically about 0.025 inches (about 600 μm). The material is then drawndown to the final gauge. The material draw down ratio is typically about21:1 for 0.8 mil (20 μm) films. A vacuum box or air knife can be used topin the melt exiting the die opening to a primary chill roll maintainedat about 90° F. (32 C). The resulting polymer film is collected on awinder. The film thickness can be monitored by a gauge monitor, and thefilm can be edge trimmed by a trimmer. One or more optional treaters canbe used to surface treat the film, if desired. Such chill roll castingprocesses and apparatus are well known in the art, and are described,for example, in The Wiley-Encyclopedia of Packaging Technology, SecondEdition, A. L. Brody and K. S. Marsh, Ed., John Wiley and Sons, Inc.,New York (1997). Although chill roll casting is one example, other formsof casting can be used.

In another aspect, films containing the polymer blend composition,monolayer or multilayer, may be formed using blown techniques, i.e. toform a blown film. For example, the composition can be extruded in amolten state through an annular die and then blown and cooled to form atubular, blown film, which can then be axially slit and unfolded to forma flat film. As a specific example, blown films can be prepared asfollows. The polymer blend composition is introduced into the feedhopper of an extruder, such as a 63.5 mm Egan extruder that iswater-cooled, resistance heated, and has an L/D ratio of 24:1. The filmcan be produced using a 15.24 cm Sano die with a 2.24 mm die gap, alongwith a Sano dual orifice non-rotating, non-adjustable air ring. The filmis extruded through the die into a film that was cooled by blowing aironto the surface of the film. The film is drawn from the die typicallyforming a cylindrical film that is cooled, collapsed and optionallysubjected to a desired auxiliary process, such as slitting, treating,sealing of printing. The finished film can be wound into rolls for laterprocessing, or can be fed into a bag machine and converted into bags. Aparticular blown film process and apparatus suitable for forming filmsaccording to embodiments of the present invention is described in U.S.Pat. No. 5,569,693. Of course, other blown film forming methods can alsobe used.

In another aspect, the invention relates to any polymer productcontaining the polymer blend composition produced by methods known inthe art. In addition, this invention also includes products having otherspecific end-uses, such as film-based products, which include stretchfilms, bags (i.e. shipping sacks, trash bags and liners, industrialliners, and produce bags), flexible and food packaging (e.g., fresh cutproduce packaging, frozen food packaging), personal care films pouches,medical film products (such as IV bags), diaper backsheets andhousewrap. Products may also include packaging as bundling, packagingand unitizing a variety of products including various foodstuffs, rollsof carpet, liquid containers and various like goods normallycontainerized and/or palletized for shipping, storage, and/or display.Products may also include surface protection applications, with orwithout stretching, such as in the temporary protection of surfacesduring manufacturing, transportation, etc. There are many potentialapplications of articles and films produced from the polymer blendcompositions described herein.

Alternatively, or additionally, the mVLDPE can be blended with LLDPE,EVA, EMA, either in addition to, or instead of, the LDPE, if desired, inthe blends, films, and article described herein.

The advantageous properties described above, as well as others that oneskilled in the art will appreciate from the present disclosure, areillustrated herein in the following examples.

5. EXAMPLES

Materials and Methods

Metallocene catalysts for the polymerization of the inventive VLDPE wereprepared according to the methods as described above for an unbridgedbis-Cp structure (such as a_bis(1,3-methyl-n-butyl cyclopentadienyl)zirconium dichloride).

In certain examples, various properties of the polymers were measuredaccording to the following test procedures, and it is understood thatwhenever these properties are discussed in this specification and in theclaims, such properties are to be measured in accordance with theseprocedures.

Tensile strength values were measured (machine direction (“MD”) andtransverse direction (“TD”)) in accordance with ASTM D882-95A, exceptthat film gauge was measured using ASTM D374-94 Method C, except thatthe micrometer calibration was performed annually with a commerciallyavailable gauge block (Starret Webber 9, JCV1&2). As reflected in TableIV, tensile values were measured at yield MD and TD, 200% MD and TD andUltimate Tensile MD and TD.

The ACD protocol is an analytical-scale TREF (Temperature Rising ElutionFractionation) test for semi-crystalline copolymers to characterize thecomposition distribution (CD). A sample is dissolved in a good solvent,cooled slowly to allow crystallization on a support, and thenre-dissolved and washed from the support by heating during elution.Polymer chains are fractionated by differences in their crystallizationtemperature in solution, which is a function of composition (and defectstructure). A mass detector provides concentration vs. elutiontemperature data; CD characterization is obtained by applying acalibration curve (i.e., mole % comonomer vs. temperature) establishedusing narrow-CD standards. Two in-house Visual Basic programs are usedfor data acquisition and analysis.

There are really two distributions provided by the ACD test:

Solubility Distribution (weight fraction vs. solubilitytemperature)—measured directly.

Composition Distribution (weight fraction vs. comonomercontent)—obtained by applying the calibration curve to the solubilitydistribution.

Emphasis is usually placed on characterization of the CD. However, thesolubility distribution can be of equal or greater importance when:

A calibration curve has not been established for the polymer ofinterest.

The MW of the sample is low, or the MWD is broad enough that asignificant portion of the sample is low MW (M<20 k). Under thesecircumstances, the reported CD is influenced by the MW-dependence ofsolubility. The calibration curve must be corrected for the effect of MWto give the true CD, which requires a priori knowledge of the relativeinfluence of MW and composition on solubility for a given sample. Incontrast, the solubility distribution correctly accounts forcontributions from both effects, without trying to separate them.

Note that the solubility distribution should depend on solvent type andcrystallization/dissolution conditions. If correctly calibrated, the CDshould be independent of changes in these experimental parameters.

Composition Distribution Breadth Index (CDBI) was measured using thefollowing instrumentation: ACD: Modified Waters 150-C for TREF(Temperature Rising Elution Fractionation) analysis (includescrystallization column, by-pass plumbing, timing and temperaturecontrollers); Column: 75 micron glass bead packing in (High PressureLiquid Chromotography) HPLC-type column; Coolant: Liquid Nitrogen;Software: “A-TREF” Visual Basic programs; and Detector: PolymerLaboratories ELS-1000. Run conditions for the CDBI measurements were asfollows:

GPC Settings

Mobile phase: TCE (tetrachlororethylene) Temperature: column compartmentcycles 5-115° C., injector compartment at 115° C. Run time: 1 hr 30 minEquilibration time: 10 min (before each run) Flow rate: 2.5 mL/minInjection volume: 300 μL Pressure settings: transducer adjusted to 0when no flow, high pressure cut-off set to 30 bar

Temperature Controller Settings

Initial Temperature: 115° C. Ramp 1 Temperature:  5° C. Ramp time = 45min Dwell time = 3 min Ramp 2 Temperature: 115° C. Ramp time = 30 minDwell time = 0 min

Alternative temperature controller settings if two peaks are notexhibited in a TREF measurement.

Initial Temperature: 115° C. Ramp 1 Temperature:  5° C. Ramp time = 12hrs Dwell time = 3 min Ramp 2 Temperature: 115° C. Ramp time = 12 hrsDwell time = 0 min

In some case, longer ramp times may be needed to show two peaks in aTREF measurement.

ELS Settings

Nebulizer temperature: 120° C. Evaporator temperature: 135° C. Gas flowrate: 1.0 slm (standard liters per minute) Heated transfer linetemperature: 120° C.

Melt Index was determined according to ASTM D-1238-95. Melt index isreported in units of g/10 min, or the numerically equivalent units ofdg/min.

Density (g/cm³) was determined using chips cut from plaques compressionmolded in accordance with ASTM D-1928-96 Procedure C, aged in accordancewith ASTM D618 Procedure A, and measured according to ASTM D1505-96.

In measuring the 1% Secant, the procedures in ASTM D882-95A werefollowed, except that the film gauge was measured according to ASTMD374-94 Method C, except that the micrometer calibration was performedannually with a commercially available gauge block (Starret Webber 9,JCV1&2).

In measuring Elmendorf Tear, the procedures in ASTM D1922-94a were used,except that the film gauge was measured according to ASTM D374-94 MethodC, except that the micrometer calibration was performed annually with acommercially available gauge block (Starret Webber 9, JCV1&2).

Dart Drop values were measured using the procedures in ASTM D1709-98Method A, except that the film gauge was measured according to ASTMD374-94 Method C, except that the micrometer calibration was performedannually with a commercially available gauge block (Starret Webber 9,JCV1&2).

Haze was measured in accordance with ASTM D1003-95.

Gloss was measured in accordance with ASTM D2457-90.

Total Energy was measured in accordance with ASTM D4272-90.

The test used to measure “puncture” values simulates the poking of afinger or bottle through a plastic film, and is a recognized method oftesting garbage bags. The testing procedure is available from UnitedTesting Machines, and is denoted PLFL-201.01. Generally, the testmeasures the force and energy necessary to puncture a plastic film witha gauge of 0.20-10.0 mils (50 to 250 μm). For puncture measurements, afilm sample is placed in a clamp approximately 4 inches (10 cm) wide. Aplunger with a ¾″ tip (19 mm) is plunged through it at a constant speedof 10 in/min (25 cm/min). A United Testing Machine SFM-1 is used, and iscalibrated annually by the manufacturer. Before testing, samples areconditioned at 23° C. and 50% relative humidity for at least 40 hoursfollowing fabrication. The sample is cut across the transverse direction(TD) bubble 6″ (15 cm) side and in the case for blown film separated.Prior to testing, each sample is gauged, with the average thicknessrecorded in mils, taken from the gauge micrometer data sheet. Theaverage gauge of the sample area is used in the test resultscalculations. The average peakload and break energy values of 5specimens are used to compile the final test results for each sample.

Polydispersity or molecular weight index (Mw/Mn) is calculated based onthe ratio of weight average molecular weight (Mw) and number averagemolecular weight (Mn) by size exclusion chromatography.

Hot tack strength was measured in accordance with the followingprocedure. The hot tack samples were 15 mm wide specimens cut fromoriginal films. The samples were back-taped (laminated) with PET toavoid rupture at the transition of the seal and elongation or stickingto the seal bars. A Hot Tack Tester 3000, from J&B, was employed to makethe seal, using a seal bar pressure of 0.5 MPa, and a seal time of 0.5s. The hot tack strength was then determined, after a cooling time of0.4 s and at a peel speed of 200 mm/min. Gauge: film gauge was measuredaccording to ASTM D374-94 Method C, except that the micrometercalibration was performed annually with a commercially available gaugeblock (Starret Webber 9, JCV1&2).

Shrink (%) was determined in the machine direction (MD) and transversedirection (TD) as follows. A 100 mm circle is cut from the film. Themachine direction is marked, then the specimen is talced and thenheated. The amount of shrinkage is measured in both MD and TD, and isreported as % MD shrinkage and % TD shrinkage.

For measurements of film properties, the film samples were annealed byheating for 48 hours at 140° F. (60° C.) prior to testing.

EXAMPLE 1

A commercial scale gas phase reactor system was operated under condensedmode conditions over a 24-hour period. Table I summarizes the reactionconditions for this 24-hour period. The measured densities of thepolyethylene polymers produced over that period ranged from 0.9090 to0.9124 g/cm³.

TABLE I LOW HIGH AVG Reaction Rate (klbs/hr) 8.8 11.5 9.9 (kg/hr) 4.0 ×10³ 5.22 × 10³ 4.5 × 10³ Total Catalyst Feed (lbs/hr) 0.95 1.73 1.27(kg/hr) 0.43 0.785 0.576 Reactor Temperature (° C.) 78.8 80.0 80.3Reactor Pressure (psig) 252 268 259 (MPa) 1.74 1.84 1.79 Ethylene Feed(lbs/hr) 8375 10586 9156 (kg/hr) 3799 4802 4153 Hexene Feed (lbs/hr) 8511243 1052 (kg/hr) 386 564 477 Hydrogen Feed (lbs/hr) 0.1423 0.25460.1963 (g/hr) 64.55 115.5 89.04 C₆/C₂ Mole Ratio 0.239 0.0249 0.0250C₂/H₄ Partial Pressure 168 182 172 C₆/C₂ Flow Ratio 0.0958 0.1261 0.1146Superficial Velocity (ft/s) 2.00 2.09 2.05 (cm/s) 61.0 63.7 62.5 BedLevel (ft) 35.6 39.6 37.5 (m) 10.9 12.1 11.4 Mid Bed Density 34.0 39.137.4 Distributor Plate DP (psi) 2.56 9.6 7.67 (kPa) 17.7 66 52.9 CycleGas Cooler DP (psi) 8.9 12.6 10.4 (kPa) 61 86.9 71.7 Catalyst FeederSpeed (rpm) 388 519 434

EXAMPLE 2

A different gas phase reactor system from the system in Example 1 wasoperated to produce VLDPEs of this invention. Table II summarizesreaction conditions for two different runs, as well as properties of theresulting polymers. As reflected in Table II, the densities of thepolymers were 0.9118 and 0.9121 g/cm³.

TABLE II Run 1 Run 2 QC Lab Data MI (g/10 min) 1.02 1.03 MIR (HLMI/MI)16.69 17.13 Density (g/cm³) 0.9118 0.9121 Bulk Density (g/cm³) 0.45000.4494 APS (μm) 997 921 COV (%) 38.8 38.2 PSD < 250 μ (%) 1.073 1.232PSD < 125 μ (%) 0.267 0.175 Pan (%) 0.042 0.027 Fines (<125 μm) (%)0.267 0.175 Flow Time (s) 7.93 7.81 MCL Data Ash (ppm) 144 137 Zr byICPES (ppm) 0.5163 0.5187 Al by ICPES (ppm) 15.5 14.9 Process Data ProdRate (klbs/hr) 154 172 (kg/hr) 6.99 × 10⁴ 7.81 × 10⁴ Hydrogen (ppm) 149153 Ethylene (mol %) 70.1 70.0 Hexene (mol %) 1.70 1.73 Butene (mol %)0.00 0.00 C₂ PP (psia) 220.4 220.2 (MPa) 1.520 1.518 H₂/C₂ ConcentrationRatio 2.13 2.19 H₂/C₂ Flow Ratio 0.017 0.021 C₆/C₂ Concentration Ratio0.243 0.247 C₆/C₂ Flow Ratio 0.119 0.115 C₄/C₂ Concentration Ratio0.0000 0.0000 C₄/C₂ Flow Ratio 0.000 0.000 Temperature (° F.) 175.0175.0 (° C.) 79.4 79.4 Bed Weight (lbs) 593 594 (kg) 269 269 Res Time(hrs) 3.88 3.45 Gas Velocity (ft/s) 2.25 2.25 (cm/s) 68.6 68.6 Plate dP(“H₂O) 26.5 26.2 (cm H₂O) 67.3 66.5 Cooler dP (psig) 0.78 0.78 (kPa) 5.45.4 RX Pressure (psig) 299.6 299.6 (MPa) 2.066 2.066 C₂ Feed (lb/hr)193.7 211.9 (kg/hr) 87.86 96.12

EXAMPLE 2a

Table IIA is one example of the reactor conditions to produce oneembodiment of a m-VLDPE of the present invention having a melt index of12.28 dg/min.

TABLE IIA Reactor Process Data Grade ECD-330 Number of Hourly DataPoints 10 PMX Database Tag and Name Production Rate R1C218 Klbs/hr 77.2Catalyst Rate R1Q218 lbs/hr 9.6 Cat Productivity RPM Calc lb/lb 8447 RxTemperature R1C163 oF 176.0 Rx Pressure R1P177 psig 304.1 InletTemperature R1T166 oF 95.6 Dew Point-Inlet R1TDELTA oF 50.7 % CondensedR1WTPCT wt % 9.9 Superficial Velocity R1C944 ft/sec 2.49 Bed WeightR1W176 Klbs 140.2 Bed Height R1D174 ft 48.5 Ethylene Part Pres R1P486psia 186.9 Ethylene Conc R1V486 mole % 58.64 Hexene Conc R1V482 mole %1.65 H2 Conc R1A881B ppm 509 Isopentane Conc R1V48A mole % 7.19 NitrogenConc R1V483 mole % 31.80 H2/C2═ R1H2C2E ppm/mol 8.67 C6═/C2═ R1Q489mol/mol 2.81 Ethylene Flow R1B100 Klbs/hr 67.0 Hexene Flow R1B104Klbs/hr 9.73 Hydrogen Flow R1B107 lbs/hr 6.16 Isopentane Flow R1F317Klbs/hr 225 C6═/C2═ Flow Ratio R1R104 lb/lb 0.160 H2/C2═ Flow RatioR1R107 lb/Klb 0.092 Rx1 Bed FBD/ SBD R1D175 Ratio 0.78 Rx1 Lower FBDR1P171 lb/ft3 18.9 Rx1 Upper FBD R1P172 lb/ft3 17.4 Rx1 Avg Filter FBDR1C171 lb/ft3 17.9 Rx1 Cat Pct Activity R1Q587 Pct 59 Rx1 IPDS Drop/hrR1C174SP Drop/Hr 24.2 Rx1 Bed Res. Time R1C176 Hours 1.86 Screw Recov.Flow 05C306 klb/hr 5.01 Sulzer Recov. Flow R1F419 lb/hr 551 Rx1 N2Purger Wt 05W461 klbs 145.7 Rx1 Stm Purger Wt 05W487 klbs 27.3 Calc FBDw/Wt&Ht Calc lb/ft3 17.5 Calc FBD/SBD Calc Ratio 0.76 Space Time YieldSTY lb/hr/ft3 9.6 Residence Time Calc hr-1 1.86 Auburn Cat Prod R1Q588klb/lb 7.23 Rx1 Flare Vent R1F134 klb/hr 0.000 Rx1 Vent to Purger R1F180klb/hr 0.000 Rx1 Composite Vent R1B135 klb/hr 0.000 Lab Data Melt Index35LR101 dg/min 12.28 Gradient Density 35LR102 g/cc 0.9107 Bulk Density35LR104 lb/ft3 23.0 APS 35LR107 inches 0.043 Fines (<120 mesh) 35LR110wt % 0.04 Ash 35LR105 ppm 105 Normal Cat Prod lb/lb 7488 (for 175 psiaC2═) at C2PP{circumflex over ( )}1.83. Bed Weight FBD * BedHt 143530ResTime Bed Wt/ProdRate 1.86

EXAMPLE 3

Certain VLDPE polymers of the invention were prepared using the gasphase polymerization using metallocene catalyst systems as describedherein. Films were formed from these polymers. The invention films areidentified below as Samples A and G. Sample A was made in the reactorsystem of Example 1, and Sample G was made in the reactor system ofExample 2. The co-monomers used to make Samples A and G were ethyleneand hexene. Fluidized gas phase reactors were operated to produce theresulting copolymers.

The polymerizations were conducted in the continuous gas phase fluidizedbed reactors described in Examples 1 and 2. The fluidized beds of thosereactors were made up of polymer granules. The gaseous feed streams ofethylene and hydrogen were introduced below each reactor bed into therecycle gas line. Hexene comonomer was introduced below the reactor bed.An inert hydrocarbon (isopentane) was also introduced to each reactor inthe recycle gas line, to provide additional heat capacity to the reactorrecycle gases. The individual flow rates of ethylene, hydrogen andhexene comonomer were controlled to maintain fixed composition targets.The concentrations of the gases were measured by an on-line gaschromatograph to ensure relatively constant composition in the recyclegas stream.

The solid catalyst was injected directly into the fluidized beds usingpurified nitrogen. The catalyst injection rates were adjusted tomaintain a constant production rate. The reacting beds of growingpolymer particles were maintained in a fluidized state by a continuousflow of the make up feed and recycle gas through each reaction zone. Tomaintain constant reactor temperatures, the temperature of the recyclegas was continuously adjusted up or down to accommodate any changes inthe rate of heat generation due to the polymerization.

The fluidized bed was maintained at a constant height by withdrawing aportion of the bed at a rate equal to the formation of the particulateproduct. The product was transferred to a purger vessel to removeentrained hydrocarbons.

EXAMPLE 4

For purposes of demonstrating the surprisingly improved toughness of theVLDPEs of this invention, a variety of films made of polyethylenepolymers made using different processes were compared. Specifically, theproperties of certain invention polymers, i.e., those made in accordancewith the gas polymerization processes corresponding to the invention,using metallocene catalysts, were compared with certain comparativepolymers, i.e., polymers made in accordance with non-invention methods.Referring now to the comparative examples, Sample B was made using acomparative polymer, specifically, a linear low density polyethylene(0.9189 g/cm³) made using metallocene catalyst in a gas phasepolymerization process. Sample C was made using a linear low densitypolyethylene (0.9199 g/cm³) made using Ziegler-Natta catalyst in a gasphase polymerization process. Sample D was made using a plastomer(0.9031 g/cm³) made using metallocene catalyst in a high pressure bulkpolymerization process. Sample E was made using a very low densitypolyethylene (0.9132 g/cm³) made using Ziegler-Natta catalyst in asolution polymerization process. Sample F was made using a very lowdensity polyethylene (0.9104 g/cm³) made using metallocene catalyst in asolution polymerization process.

Each of the polymers was formed into a film. The processing conditionsfor the preparation of the films reported in Table V are set forth inTable III below. The properties of each of the films were then measured.The properties of the films reported in Table V are set forth in TableIV.

TABLE III Measured Properties A B C D E F G Melt Temperature (° F.) 385388 377 397 381 377 392 (° C.) 196 198 192 203 194 192 200 Extruder HeadPress (psi) 3520 3490 3120 4490 3220 3190 3780 (MPa) 24.3 24.1 21.5 31.022.2 22.0 26.1 Extruder Speed (rpm) 46.4 46.4 46.4 41.8 46.6 43.3 45.4Line Speed (ft/min) 123 121 119 119 119 119 119 (m/min) 3.75 3.67 3.633.63 3.63 3.63 3.63 Production Rate (lbs/hr) 155 152 152 154 151 152 153(kg/hr) 70.3 68.9 68.9 69.9 68.5 68.9 69.4 Frost Line Height (in) 20 1815 25 16 18 19 (cm) 51 46 38 63 41 46 48 Extruder Drive Load 55.4 55.749.1 59.6 47.5 47.6 56.6 (%) Motor Load/Prod. 0.357 0.366 0.323 0.3870.315 0.313 0.37 Rate Horsepower 13.6 13.7 12 13.2 11.7 10.9 13.6 Prod.11.38 11.11 12.63 11.67 12.86 13.93 11.21 Rate/Horsepower Torque (hp ·rpm) 0.293 0.295 0.26 0.316 0.251 0.252 0.3

TABLE IV Measured Properties A B C D E F G Density (g/cm³) Molded 0.91290.9189 0.9199 0.9031 0.9132 0.9104 0.9114 Rheology MI (I2) 1.07 1.171.10 1.09 1.00 0.96 0.97 HLMI 18.50 19.14 30.03 18.03 30.37 35.54 17.04(I21) Ratio 17.29 16.36 27.30 16.54 30.37 37.02 17.56 (I21/I2) MI Swell1.12 1.08 1.17 1.01 1.14 1.23 1.10 Hexene Content Wt % 9.6 7.1 10.2GPC-HT Mn 50612 48653 52016 Mw 100908 100064 102647 Mw/Mn 1.99 2.06 1.97Mz/Mw 1.66 1.69 1.61 Mz + 1/Mw 2.46 2.52 2.29 ACD CDBI 64.5 6.7 55.3 %Solubles 0.6 0.6 1.1 DSC (° C.) 1^(st) melt-Peak 2^(nd) peak 3^(rd) peak2^(nd) melt-Peak 118.34 120.70 124.56 118.00 105.68 117.83 2^(nd) peak103.41 109.62 99.64 123.25 101.72 3^(rd) peak 103.62 ΔH (J/g) 112.06126.96 128.45 94.76 112.45 108.61 109.84 Crystallization- Peak 2^(nd)peak 3^(rd) peak Tear-Intrinsic 346 351 460 237 546 433 327 (g/mil)

The films made of invention polymers (Samples A and G) were tested inaccordance with the test procedures discussed above. The same propertiesof the comparative films, made of polymers made using non-inventionprocesses, were also measured, to demonstrate certain improvedproperties resulting from the invention. The results of thesemeasurements are shown in Table V.

The films made of invention polymers showed a remarkable improvementover comparative polymers in Dart Drop values, which measure the energythat causes a polymer film to fail under specified conditions of impactof a free-falling dart. As reflected in Table V, Dart Drop values forSamples A and G were 623 and 1,289 g/mil, respectively. These Dart Dropvalues were over 50% greater than the Dart Drop values for all the filmsmade of polymers made using solution polymerization processes. That is,Dart Drop for Sample E (a film made of a VLDPE made using Ziegler-Nattacatalyst in a solution polymerization process) was 338 g/mil, and DartDrop for Sample F (a film made of a VLDPE made using metallocenecatalyst in a solution polymerization process) was 491 g/mil. The DartDrop values of the films made of invention polymers were also over 50%greater than the Dart Drop values for films made of polymers made usingother gas phase polymerization processes. Dart Drop for Sample B (a filmmade of an LDPE made using metallocene catalyst in a gas phasepolymerization process) was 362 g/mil, and Dart Drop for Sample C (afilm made of an LDPE made using Ziegler-Natta catalyst in a gas pleasepolymerization process) was 112 g/mil. The invention polymers alsoshowed improvement in Puncture properties, which reflect the resistanceof a stretch wrap film to the penetration of a probe. As reflected inTable V, for Samples A and G, Puncture Peak Force values were 11.55 and9.96 lb/mil, respectively and Puncture Break Energy values were 40.40and 32.52 in-lb/mil, respectively. These values were greater than thevalues for all the comparative films made of polymers made usingsolution polymerization processes. That is, for Sample E (a film made ofan VLDPE made using Ziegler-Natta catalyst in a solution polymerizationprocess), the Peak Force was 10.02 lb/mil, and the Puncture Break Energywas 34.33 lb/mil. For Sample F (a film made of a VLDPE made usingmetallocene catalyst in a solution polymerization process), the PeakForce was 10.70 lb/mil, and the Puncture Break Energy was 35.29in-lb/mil. The Puncture properties of films made of the inventionpolymers were also higher than the Puncture properties of polymers madeusing other gas phase polymerization processes. For Sample B (a filmmade of an LDPE made using metallocene catalyst in a gas phasepolymerization process), the Peak Force was 9.98 lb/mil and the PunctureBreak Energy 31.25 in-ft/mil. For Sample C (a film made of LDPE madeusing Ziegler-Natta catalyst in a gas phase polymerization process) thePeak Force was 8.13 lb/mil and the Puncture Break Energy was 23.46in-ft/mil.

TABLE V A B C D E F G Tensile @ Yield 1078 1335 1447 738 1087 934 1054MD (psi) Tensile @ Yield 1080 1397 1618 713 1118 921 1050 TD (psi)Tensile at 200 1911 1901 1905 1812 2269 2684 1897 % MD (psi) Ultimate11,232 10,550 8,603 10,579 9,586 9,218 11,598 Tensile MD (psi) Ultimate9,197 8,012 6,240 10,778 6,748 8,597 9,463 Tensile TD (psi) Elongation @6.8 6.2 5.9 8.8 6.5 7.3 6.9 Yield MD (%) Elongation @ 6.7 6.2 5.9 8.06.2 6.5 6.8 Yield TD (%) Break 474 518 545 439 446 458 480 Elongation MD(%) Break 617 627 740 592 711 736 618 Elongation TD (%) 1% Secant 25,30036,270 37,330 14,630 27,360 22,520 25,080 Modulus MD (psi) 1% Secant27,500 39,380 47,020 17,030 30,480 23,330 26,780 Modulus TD (psi)Elmendorf 202 247 225 159 352 133 178 TearMD (g/mil) Elmendorf 396 439764 362 696 475 392 TearTD (g/mil) Dart Drop 773 442 145 1723 422 6241651 Method A(g) Dart Drop 623 362 112 1336 338 491 1289 Method A(g/mil) Gauge (mil) Average 1.24 1.22 1.29 1.29 1.25 1.27 1.28 Low 1.101.13 1.15 1.09 1.15 1.19 1.14 High 1.34 1.31 1.40 1.52 1.34 1.36 1.38Haze (%) 7.7 17.7 14.3 1.0 6.9 3.3 9.3 Gloss 45 degree 58 44 51 92 70 7658 (I/I) 191 47 208 178 197 212 >214 Puncture 14.32 12.17 10.48 14.1912.53 13.58 12.75 Peak Force (lb) Puncture 11.55 9.98 8.13 11.00 10.0210.70 9.96 Peak Force (lb/mil) Break 50.09 38.13 30.26 48.09 42.92 44.8241.66 Energy (in-lb) Break 40.40 31.25 23.46 37.28 34.33 35.29 32.54Energy (in- lb/mil) Total Energy @ 3.01 2.34 1.79 2.85 2.42 1.86 3.07−29° F. (ft/lb) Total Energy @ * 4.57 1.80 * 2.73 4.61 * −RT (ft/lb)Shrink MD (%) 42 45 61 46 72 79 46 Shrink TD (%) −4 −4 −14 −8 −23 −10−9 * greater than capacity

EXAMPLE 5

As reflected in Table VI, the Dart Drop of films made of inventionpolymers was also substantially higher than the Dart Drop of films madeof higher density polymers made from a gas phase polymerization processusing metallocene catalyst. In this example, the properties of unheatedfilms made from invention VLDPEs were compared to unheated films madeusing non-invention LDPEs. Samples “AA” and “BB” were both non-inventionfilms, made from polyethylenes having a density of 0.917 and a meltindex of 3.5. Sample “AA” had a thickness of 1.54 mil average gauge,while Sample “BB” had a thickness of 0.85 mil average gauge. Samples“CC” and “DD” were invention films, made from a VLDPE. Sample “CC,” madeof a VLDPE with a melt index of 3.5 and density of 0.912, had an averagegauge thickness of 1.49, and Sample “DD,” made of a VLDPE with a meltindex of 3.5 and a density of 0.912 had an average gauge thickness of0.81. Both the invention and non-invention polymers were made using agas phase polymerization process with a metallocene catalyst system. Thedata show that, even though the invention VLDPEs had lower density thanthe non-invention LDPEs, the Dart Drop toughness of the invention VLDPEfilms were higher than the Dart Drop toughness of the non-invention LDPEfilms. Specifically, average Dart Drop (in g/mil) for invention Samples“CC” and “DD” was over 40% greater than average Dart Drop fornon-invention Samples “AA” and “BB.”

TABLE VI AA BB CC DD Dart Drop (g) 964 610 1,338 826 (g/mil) 626 717 8981,020 Gauge (mil) Average 1.49 0.81 1.54 0.85 Low 1.50 0.81 1.43 0.77High 1.56 0.88 1.54 0.85 Puncture Peak Force (lb) 16.00 10.82 15.7511.03 Peak Force (lb/mil) 10.39 12.73 10.57 13.61 Break Energy (in-lb)58.20 38.31 59.37 38.62 Break Energy (in-lb/mil) 37.79 45.07 39.85 47.68

EXAMPLE 6

Another improved property exhibited by the invention VLDPEs is superiorhot tack strength at low initiation temperatures, an important propertyfor films. At an initiation temperature of 100° C., the Samples A-Gdiscussed above were subjected to a Hot Tack test. The results are asfollows: Hot tack was 6.56 for Sample A; 0.38 for Sample B; 0.28 forSample C; 6.50 for Sample D; 2.35 for Sample E; 3.38 for Sample F; and6.90 for Sample G. Thus, it was demonstrated that Samples A and Gperformed substantially better than the other samples in the Hot Tacktests.

EXAMPLE 7

Films formed of a 12 dg/min, 0.912 g/cm³ mVLDPE film resin of thepresent invention with 5 to 40% by weight of LDPE were made according tothe procedures described herein. Both LD200 and LD270 were used; theseLDPEs are commercially available LDPE produces. The films were extrusioncoated onto Kraft paper, and the mechanical properties and sealingproperties were measured. The results are shown in Table VII formechanical properties, Table VIII for hot tack strengths, and Table IXfor heat seal strengths.

TABLE VII^((a)) Mechanical Properties 5% A 10% A 20% A 40% A 5% B 10% B20% B 40% B 100% B^((b)) MD Elmendorf Tear (g) 424 374 280 178 492 405310 206 112 TD Elmendorf Tear (g) 422 405 292 219 498 465 304 235 109Puncture Break Energy (J) 0.67 0.49 0.30 0.25 0.73 0.52 0.37 0.32 0.14^((a))A = LD200, B = LD270 ^((b))control sample (no mVLDPE)

TABLE VIII^((a)) Hot Tack Strength (N/15 mm) 5% A 10% A 20% A 40% A 5% B10% B 20% B 40% B 100% B^((b)) 100° C. 2.7 1.7 1.5 1.1 1.4 2.5 1.9 1.2 —105° C. 3.3 3.5 2.6 2.1 3.3 4.0 3.1 3.4 1.4 110° C. 3.9 4.4 3.2 3.5 3.84.1 4.4 3.5 4.2 115° C. 4.5 4.2 4.1 3.9 3.6 4.5 4.5 4.0 4.2 120° C. 4.74.6 5.4 4.2 5.0 5.8 4.2 5.1 4.1 125° C. 5.9 5.7 4.6 4.3 5.4 6.4 4.7 5.13.2 ^((a))A = LD200, B = LD270 ^((b))control sample (no mVLDPE)

TABLE IX^((a)) Heat Seal Strength (N) 5% A 10% A 20% A 40% A 5% B 10% B20% B 40% B 100% B^((b))  90° C. — 2.4 1.7 0.9 — — 1.1 1.9 —  95° C. 3.05.3 3.7 3.4 1.7 3.4 4.6 4.0 2.0 100° C. 6.7 7.4 7.5 5.3 3.1 10.5 8.0 6.63.1 105° C. 9.3 9.4 9.0 9.6 10.8 8.9 9.0 9.3 8.4 110° C. 9.6 10.0 9.89.8 10.8 12.2 9.8 10.4 11.5 115° C. 10.4 10.7 9.9 10.0 11.6 13.2 10.510.4 9.5 120° C. 11.1 11.3 10.4 10.2 14.1 15.7 11.5 11.9 10.6 125° C.11.2 12.2 10.7 10.0 12.3 14.8 12.0 12.1 10.1 130° C. 11.7 11.4 10.6 10.412.6 15.1 11.5 10.4 10.1 135° C. 11.6 12.4 9.9 10.1 12.5 14.4 10.6 11.59.7 140° C. 11.4 11.9 10.1 9.2 13.6 14.3 9.7 10.1 9.1 ^((a))A = LD200, B= LD270 ^((b))control sample (no mVLDPE)

The data in Tables VIII-IX show several advantageous properties of filmsor coatings made from LDPE/mVLDPE blends of the present invention. Allof the blends showed improved machine direction and transverse directionElmendorf Tear strength, and improved puncture break energy, compared tothe conventional LDPE film (the control sample, “100% B”). In the hottack strength measurements (Table VIII), the blends generally showedsuperior adhesion at most temperatures, and particularly at highertemperatures, compared to the LDPE control sample. Similarly, the heatseal strengths of the LDPE/mVLDPE blends were generally higher than forthe LDPE control sample at most temperatures.

EXAMPLE 8

The following materials are compared in this example:

TABLE X Material for Forming Films Tested in Tables XIa-XVIIb ProductWt. % Density, Family Grade Name* MI, g/10 min Comonomer g/cc LDPELD-200.48 7.5 0.918 EVA UL-01418 14 18 EMA TC-220 5 24 EnBA XW-25.AL 7.825 Ionomer Iotek ™ 8030 (Na) 2.8 0.956 EAA Escor ™ 5100 6.5 6.5Plastomer Exact ™ 3040 16 0.900 Mvldpe ECD-330 12 0.912 *All productsproduced by ExxonMobil Chemical Company. ECD-330 is a developmentalmaterial.

Monolayer coatings were applied using a 3.5 inch extruder. The 750 mmdiameter chill roll had a matte finish and was held at 15° C. throughoutthe run. The substrate used was 70# Kraft paper which was corona treatedat 10 kW prior to coating. The air gap was maintained at 150 mm. Targetcoating thicknesses were 15, 25 and 50 g/m².

Tests for processability were conducted according to established ETCprotocols. Resin extrudability is determined by measuring motor load,pressure, and melt temperatures at 25, 50, and 150 rpm. Resin neck-in ismeasured at 25 rpm output onto untreated paper at 25, 50, 100, and 200meters per minute (mpm) line speeds. Maximum drawdown is determined byextruding resin at 25 rpm output onto untreated paper and increasingline speed at 10 meters per minute per second acceleration

ECD-330 (12 dg/min, 0.912 g/cc) and LD200.48 (7.5 dg/min,-0.915 g/cc)were extruded in blends of 0, 20, 40, 60, 80, and 100 weight percentECD-330. ECD-330 was extruded at 100% only for processing comparisonsand the 25 and 50 g/m² coating weights. The ECD-330 used in this workwas produced at MBPP on Nov. 19, 2000. It was formulated with 200 ppmIrganox 1076.

The linear comparisons were Exact 3040 (16.5 dg/min, 0.900 g/cc), Dow3010 (5.4 dg/min, 0.921 g/cc), Dow Affinity PT1450 (7.5 dg/min, 0.902),Nova Sclair 61C (5.3 dg/min, 0.919). Exact 3040 and Nova Sclair 61C wereblended with 20 weight percent LD200.48. Dow Affinity PT1450 was run at100% and blended with 20 weight percent LD200.48. Also included in thecompetitive comparison was UL02020 (20 dg/min, 20 weight percent VA).

Films were tested for Elmendorf tear, tensile strength, and punctureresistance. 15 g/m² samples were tested for burst strength by standardprocedures for a Perkins-Bowthruck Bond Tester, Type CSR-710-64 at roomtemperature (˜25° C.) which can be used to quantify coating efficiency,or relative bond strength to the paper.

Processing Comparisons

Processing data are shown in Tables XIa and XIb. Data from the DPUT-1212evaluation is included. The motor load values at all three screw speedsoverlay indicating that the DPUT-1212 and ECD-330 had similarextrudability. As expected, adding LDPE reduces motor load. Similartrends are seen for head pressures. These results show neck-in at 100mpm and maximum drawdown, respectively, for ECD-330 and DPUT-1212. Theseproperties are also the same between the two resins.

Neck-in as a function of LDPE content in ECD-330 at four different linespeeds is given in Table XIa. There is a significant reduction inneck-in with 20 weight percent added L9200.48, but little significantchange at 40 weight percent and higher.

Motor load results for an 80/20 ECD-330/LD200.48 blend and the linearcomparative samples show that the ECD-330 blend processes more easilythan Dow 3010 and Nova Sclair 61C which can be expected with the muchlower melt indices for the LLDPE resins. Processability for the ECD-330blend is similar to the Affinity PT1450 resin and LD-blend and is moredifficult than the higher melt index Exact 3040.

At higher line speeds, the ECD-330 blend has very good neck-in which ismatched only by the Affinity PT1450/LD blend and Exact 3040. Neck-in forDow 3010, Nova Sclair 61C, and unblended PT1450 are much worse. Theresults show that maximum drawdown for the linear resins with unblendedPT1450 and Exact 3040 having the greatest attainable line speeds.ECD-330 falls third, but can be run at much greater line speed/drawdownthan Dow 3010, Nova Sclair 61C, and PT1450 with LDPE.

Physical Properties

Mechanical properties are given in Tables XIIa and XIIb for the 15 g/m²samples, Tables 3a and 3b for the 25 g/m² samples and 4a and 4b for the50 g/m² samples.

The property trends are similar for all three coating weights in theLDPE, LDPE/ECD-330 blends. The results show burst test data for the 15g/m² samples which indicates that LDPE has better adhesion to paperunder the extrusion conditions used, and further show that Elmendorftear and puncture energy are negatively affected by the addition ofLDPE.

As shown by burst test results for the linear comparative resins and anEVA, the ECD-330/LDPE blend has relatively poor adhesion to Kraft paperand is only better than the Dow Affinity PT1450. Mechanical propertiesdata for the 25 g/m² coating samples shows. Tensile break energy forECD-330 and the ECD-330/LDPE blend is relatively good. Only the Dow 3010and Nova Sclair 61C were better, which is due at least part to the muchhigher molecular weight of the LLDPE resins. Elmendorf tear, especiallyfor the unblended ECD-330, was quite good. Puncture break energy wasslightly better for ECD-330 than the other linear resins. Dow AffinityPT1450 had very good puncture resistance.

Hot Tack and Heat Seal Results

Hot tack and heat seal comparisons between ECD-330 and DPUT-1212 at 25g/m² coating weight show that ECD-330 has far superior hot tack and heatseal performance to DPUT-1212. This may be due to a slightly lower resindensity for ECD-330 or less surface oxidation. TOF-SIMS analysis of theECD-330 in this work shows surface oxygen concentration to be belowdetectable limits indicating that the resin was not degradedsignificantly during processing.

Hot tack comparisons for the ECD-330/LDPE blends at 15, 25, and 50 g/m²coating weights, respectively. The general trends in these plots is thatLD200.48 has the worst hot tack strength and increasing the amount ofECD-330 in the blend improves hot tack strength. The trends become moreevident at thicker coatings.

Nova Sclair 61C has the worst hot tack strength, followed by Dow 3010.Dow 3010 has good hot tack strength at thicker gauges, but at relativelyhigh temperatures, greater 115° C. Dow Affinity PT1450 and thePT1450/LDPE blend have slightly better hot tack strength at lowertemperatures than ECD-330, i.e. 90° C. and below, but significantlylower hot tack strength above 100° C., Exact 3040 has a similar hot tackstrength profile compared to ECD-330, but is shifted to approximately10° C. lower temperatures. As expected, UL02020 has the lowesttemperature hot tack strength.

Heat seal strengths for ECD-330/LDPE blends follow similar trends to thehot tack data. Table XVIa gives heat seal data for the ECD-330/LDPEblends at 25 g/m² coating weight. Increasing the amount of ECD-330 inthe blend improves heat seal strength slightly relative to LDPE. ECD-330as a single component has significantly better heat seal strength thanthe blends or LDPE.

Heat seal strength for the competitive linear resins at 25 g/m² coatingweight show that ECD-330 has similar seal performance to Exact 3040, butat approximately 5° C. higher temperatures. Dow 3010 and Nova Sclair 61Chave acceptable heat seals only above 110° C.

TABLE XIa Processing data for ECD-330/LD200.48 resins and blends. ECD-ECD- ECD- ECD- ECD- Resin LD200.48 330 330 330 330 330 % LD200 100 80 6040 20 0 Set Temperature (° C.) 295 295 295 295 295 295  25 RPM MotorLoad (amps) 58 62 67 71 76 83 Head Pressure (bar) 33 40 39 44 45 52Adapter Temperature 299 299 300 300 300 300 (° C.) Pipe Temperature (°C.) 296 296 296 296 296 296  50 RPM Motor Load (amps) 86 94 103 107 118131 Head Pressure (bar) 42 54 54 55 69 57 Adapter Temperature 297 299300 300 301 302 (° C.) Pipe Temperature (° C.) 295 296 297 297 297 298150 RPM Motor Load (amps) 152 165 180 193 210 229 Head Pressure (bar) 5969 72 77 79 87 Adapter Temperature 286 295 301 306 310 314 (° C.) PipeTemperature (° C.) 288 295 299 303 306 319 Output@50 rpm (kg/5 min) 6.696.84 7.00 7.08 7.23 7.36 Output at 50 RPM 80 82 84 85 87 88 (kg/hr)Specific Output 50 rpm 1.60 1.64 1.68 1.70 1.74 1.76 (kg/hr/rpm) Spec.cEnergy 328 351 376 386 417 454 Consump. (kJ/kg) Neck-in at 25 mpm 3.74.0 4.5 5.8 10.0 19.9 (cm) Neck-in at 50 mpm 3.3 3.5 3.9 4.7 7.7 23.8(cm) Neck-in at 100 mpm 3.1 3.3 3.6 4.2 6.4 EW (cm) Neck-in at 200 mpmMB MB MB 4.2 6.1 EW (cm) Max. Drawdown 124.5 141.5 171.5 218 381 **(mpm) 15 g/m² Sample Screw Speed (rpm) 27.9 27.6 27.2 27.3 26.8 19.9Neck-in (cm) 3 3.3 3.7 4 5.5 ** Motor Load (amps) 60 85 71 74 77 69 MeltPressure (bar) 31 42 43 36 35 38 Melt Temperature (° C.) 299 300 300 300300 300 25 g/m² Sample Screw Speed (rpm) 46.5 46 45.3 45.5 44.6 33.1Neck-in (cm) 3 33 3.7 4 5.8 26.5 Motor Load (amps) 85 95 101 105 102Melt Pressure (bar) 42 39 41 39 40 Melt Temperature (° C.) 300 301 300300 301 50 g/m² Sample Screw Speed (rpm) 93 92 90.6 91 89.2 66.2 Neck-in(cm) 3 3.3 3.7 4.3 6.5 23 Motor Load (amps) 113 122 135 147 160 152 MeltPressure (bar) 39 48 47 48 46 46 Melt Temperature (° C.) 300 302 303 300304 302

TABLE XIb Processing data for competitive linear resins and an EVA.Exact Dow Affinity Resin 3040 3010 PT1450 PT1450 Nova61C UL02020 % LD20020 20 20 Set Temperature (° C.) 295 295 295 295 295 240  25 RPM MotorLoad (amps) 72 92 84 77 92 70 Head Pressure (bar) 44 64 48 41 55 44Adapter Temperature 299 303 300 300 304 243 (° C.) Pipe Temperature 296299 297 297 299 240 (° C.)  50 RPM Motor Load (amps) 109 136 123 114 135100 Head Pressure (bar) 52 83 65 61 84 52 Adapter Temperature 298 308301 300 310 243 (° C.) Pipe Temperature 295 302 297 297 303 241 (° C.)150 RPM Motor Load (amps) 202 202 210 194 233 157 Head Pressure (bar) 7070 82 78 118 65 Adopter Temperature 301 301 310 306 327 243 (° C.) PipeTemperature 299 299 305 303 318 243 (° C.) Output @ 50 rpm 7.26 6.937.31 7.16 6.76 7.71 (kg/5 min) Output at 50 RPM 87 83 88 86 81 93(kg/hr) Spec. Output @ 50 rpm 1.74 1.66 1.76 1.72 1.62 1.86 (kg/hr/rpm)Specific En. Cons. 383 501 429 406 510 331 (kJ/kg) Neck-in at 25 mpm11.5 9.3 13.6 9.1 8.9 15.5 (cm) Neck-in at 50 mpm 9.1 8.8 12.7 7.3 8.115 (cm) Neck-in at 100 mpm 6.8 8.5 10.9 5.8 7.7 12 (cm) Neck-in at 200mpm 6 8.4 9.7 5.5 7.6 9 (cm) Max. Drawdown 502 264.5 506 298 249.5 >600(mpm) 15 g/m² Sample Screw Speed (rpm) 26.5 27.8 26.9 27.3 29.2 25.7Neck-in (cm) 5.8 7.9 9.3 5.4 7.4 12.3 Motor Load (amps) 70 98 85 79 10271 Melt Pressure (bar) 32 55 41 38 57 38 Melt Temperature 298 302 300300 304 244 (° C.) 25 g/m² Sample Screw Speed (rpm) 44.2 46.4 44.8 45.548.6 42.9 Neck-in (cm) 6.2 8 9.8 5.5 7.6 12 Motor Load (amps) 102 125106 127 90 Melt Pressure (bar) 38 60 44 41 60 40 Melt Temperature 299303 300 301 304 244 (° C.) 50 g/m² Sample Screw Speed (rpm) 88.4 92.889.6 91 97.2 85.8 Neck-in(cm) 7.7 8.2 10.6 6.2 8 11.6 Motor Load (amps)150 187 166 153 192 122 Melt Pressure (bar) 46 75 51 48 81 44 MeltTemperature 301 310 303 303 315 246 (° C.)

TABLE XIIa Mechanical properties for ECD-330/LDPE blends at 15 g/m²coating weights. Notebook 22249-043- 001 002 005 008 0011 014 ResinPaper LD200 ECD330 ECD330 ECD330 ECD330 % LDPE 100 80 60 40 20 CoatWeight (g/m²) 15 15 15 15 15 Tensile Strength (lb) MD 49 49 48 46 46 48TD 29 27 28 30 27 28 Tensile Strength (psi) MD 15400 13500 13400 1270012900 13200 TD 8700 770 8000 8300 7800 8000 Break Energy (in-lb) MD 3.93.3 3.3 2.9 2.6 3.0 TD 2.5 2.4 2.5 2.8 2.3 2.4 Elmendorf Tear (g) MD 6080 90 110 120 190 TD 70 90 100 120 140 210 Puncture (coat up) Peak Force(lb) 10.6 10.8 11.8 10.2 10.6 11.0 Break Energy (in-lb) 1.1 1.8 1.5 1.71.8 1.9 Puncture (paper up) Peak Force (lb) 10.3 10.9 12.5 11.1 11.611.7 Break Energy (in-lb) 1.2 1.3 1.4 1.4 1.4 1.4 Burst Test Coatingefficiency (%) 94 86 98 74 61

TABLE XIIb Mechanical properties for competitive resins at 15 g/m²coating weights. Notebook 22249-043- 020 023 026 029 032 035 Resin ExactAffinity 3040 Dow3010 PT1450 PT1450 Nova61C UL02020 % LDPE 20 20 20 CoatWeight (g/m²) 15 15 15 15 15 15 Tensile Strength (lb) MD 45 49 45 45 4742 TD 26 28 25 24 26 27 Tensile Strength (psi) MD 12100 13100 1180012000 12400 11000 TD 7200 7900 6700 6700 7300 7500 Break Energy (in-lb)MD 2.3 3.6 2.3 2.4 3.2 1.8 TD 2.0 2.4 2.0 1.7 2.2 2.2 Elmendorf Tear (g)MD 230 160 250 160 130 80 TD 220 210 280 210 150 120 Puncture (coat up)Peak Force (lb) 11.2 12.1 10.4 11.9 11.0 11.2 Break Energy (in-lb) 2.62.1 4.6 2.3 2.2 2.2 Puncture (paper up) Peak Force (lb) 11.1 12.0 11.411.9 11.9 11.0 Break Energy (in-lb) 1.7 1.6 1.8 1.7 1.6 1.7 Burst TestCoating efficiency (%) 94 98 33 34 100 100

TABLE XIIIa Mechanical properties for ECD-330/LDPE blends at 25 g/m²coating weights. Notebook 22249-043- 003 006 009 012 015 018 Resin LD200ECD330 ECD330 ECD330 ECD330 ECD330 % LDPE 100 80 60 40 20 0 Coat Weight(g/m²) 25 25 25 25 25 25 Tensile Strength (lb) MD 49 50 50 45 47 47 TD30 28 28 29 26 28 Tensile Strength (psi) MD 12600 12900 12900 1180011700 10000 TD 7600 7300 7400 7500 6800 7400 Break Energy (in-lb) MD 3.33.4 3.2 2.4 2.7 2.4 TD 2.5 2.4 2.4 2.4 1.8 2.3 Elmendorf Tear (g) MD 90100 120 170 270 410 TD 100 110 150 200 290 410 Puncture (coat up) PeakForce (lb) 13.3 12.1 11.0 11.5 12.5 12.4 Break Energy (in-lb) 1.6 2.32.4 2.3 2.5 3.5 Puncture (paper up) Peak Force (lb) 12.4 11.6 12.9 12.212.7 11.8 Break Energy (in-lb) 1.5 1.3 1.5 1.7 1.7 2.5

TABLE XIIIb Mechanical properties for competitive resins at 25 g/m²coating weights. Notebook 22249-043- 021 024 027 030 033 036 Resin ExactAffinity 3040 Dow3010 PT1450 PT1450 Nova61C UL02020 % LDPE 20 20 20 CoatWeight (g/m²) 25 25 25 25 25 25 Tensile Strength (lb) MD 47 47 46 44 4546 TD 25 28 26 24 24 24 Tensile Strength (psi) MD 11200 11300 1100010600 10700 10700 TD 6100 7300 6400 6000 5900 6000 Break Energy (in-lb)MD 2.3 3.2 2.3 2.1 2.8 2.0 TD 1.9 2.3 2.0 1.8 2.3 1.8 Elmendorf Tear (g)MD 310 210 390 230 180 100 TD 340 270 390 300 220 130 Puncture (coat up)Peak Force (lb) 12.1 11.9 11.4 9.6 10.7 10.9 Break Energy (in-lb) 3.22.6 7.9 10.0 2.6 2.6 Puncture (paper up) Peak Force (lb) 11.5 11.7 11.312.6 13.9 10.4 Break Energy (in-lb) 2.2 2.0 4.0 2.1 1.8 1.7

TABLE XIVa Mechanical properties for ECD-330/LDPE blends at 50 g/m²coating weights. Notebook 22249-043- 004 007 010 013 016 019 Resin LD200ECD330 ECD330 ECD330 ECD330 ECD330 % LDPE 100 80 60 40 20 0 Coat Weight(g/m²) 50 50 50 50 50 50 Tensile Strength (lb) MD 47 49 51 50 47 47 TD30 30 26 31 29 31 Tensile Strength (psi) MD 9700 9600 10500 9700 89008200 TD 6200 6200 5500 6400 5900 6500 Break Energy (in-lb) MD 3.0 3.03.2 3.0 2.5 2.3 TD 2.6 2.7 1.9 2.8 2.3 2.6 Elmendorf Tear (g) MD 120 160210 320 530 740 TD 140 200 270 410 570 1280 Puncture (coat up) PeakForce (lb) 11.8 11.3 11.9 11.7 11.9 12.4 Break Energy (in-lb) 3.1 3.83.7 4.4 7.8 16.0 Puncture (paper up) Peak Force (lb) 11.9 12.9 12.5 13.013.0 12.3 Break Energy (in-lb) 2.2 2.3 2.6 2.8 3.3 9.3

TABLE XIVb Mechanical properties for competitive resins at 50 g/m²coating weights. Notebook 22249-043- 022 025 028 031 034 037 Resin ExactAffinity 3040 Dow3010 PT1450 PT1450 Nova61C UL02020 % LDPE 20 20 20 CoatWeight (g/m²) 50 50 50 50 50 50 Tensile Strength (lb) MD 47 49 47 47 4746 TD 29 29 27 28 27 26 Tensile Strength (psi) MD 9200 9100 8500 88008900 8500 TD 5800 5700 5300 5600 5500 5200 Break Energy (in-lb) MD 2.13.4 2.1 2.5 3.1 1.9 TD 2.5 2.6 2.2 2.3 2.2 2.1 Elmendorf Tear (g) MD 560400 680 460 340 150 TD 560 560 720 590 400 200 Puncture (coat up) PeakForce (lb) 12.7 12.4 13.1 12.6 12.9 11.2 Break Energy (in-lb) 5.6 4.440.6 21.4 4.3 6.7 Puncture (paper up) Peak Force (lb) 12.6 12.7 12.413.4 13.3 12.5 Break Energy (in-lb) 3.3 3.1 24.2 9.1 4.4 2.6

TABLE XVa Hot tack and heat seal data for ECD-330/LDPE blends at 15 g/m²coating weights. Notebook 22249-043- 002 005 008 011 014 Resin LD200ECD330 ECD330 ECD330 ECD330 % LDPE 100 80 60 40 20 Coat weight (g/m²)Temp. (° C.) 15 15 15 15 15 Hot Tack (N) 90 0.02 0.02 0.03 0.02 0.2 950.39 1.96 3.66 4.16 3.27 100 4.97 5.06 5.51 5.04 5.20 105 5.74 6.12 6.495.56 5.76 110 4.88 6.52 7.76 6.62 6.59 115 4.61 5.98 6.20 7.26 7.19 1204.12 4.92 5.95 6.72 7.77 125 3.31 4.16 4.34 5.06 5.88 130 2.67 3.30 3.563.70 4.45 Heat Seal (lbs) 85 0.14 0.21 0.16 0.53 0.16 90 0.95 0.97 1.681.15 0.67 95 1.61 0.90 1.61 1.17 1.06 100 2.18 1.09 2.60 1.40 1.36 1052.20 2.40 3.43 1.93 2.02 110 2.60 2.48 3.36 2.71 2.61 115 2.28 2.87 3.093.18 2.84 120 2.40 2.46 3.07 3.05 2.83

TABLE XVb Hot tack and heat seal data for competitive resins at 15 g/m²coating weights. Notebook 22249-043- 020 023 026 029 032 035 Resin DowNova UL02020 Ex. 3040 3010 PT1450 PT1450 61C % LDPE 20 20 20 0 Coatweight (g/m²) Temp. (° C.) 15 15 15 15 15 15 Hot Tack (N) 60 0.04 650.60 70 3.06 75 5.00 80 0.02 0.02 0.02 5.81 85 2.49 0.84 0.08 5.12 904.98 0.02 1.98 1.54 4.12 95 5.86 0.02 2.30 2.68 3.70 100 8.08 0.02 3.843.95 0.03 105 8.81 4.60 5.14 5.23 0.03 110 8.24 6.19 5.72 4.79 4.63 1156.70 6.74 5.89 4.34 6.80 120 5.25 7.41 5.80 6.02 7.14 125 3.66 7.51 4.483.39 6.03 130 7.92 2.54 5.85 135 7.62 140 5.63 Heat Seal (lbs) 60 0.1365 1.29 70 2.14 75 0.09 2.29 80 1.58 0.35 0.08 2.41 85 2.96 0.83 0.582.66 90 3.21 0.91 0.94 2.50 95 4.27 0.18 0.93 1.05 0.13 2.54 100 4.080.38 1.13 1.15 0.22 105 0.40 1.32 1.62 0.54 110 1.62 1.65 1.67 115 2.063.66 120 3.04 3.38 125 3.22 3.98 130 3.38

TABLE XVIa Hot tack and heat seal data for ECD-330/LDPE blends at 25g/m² coating weights. Notebook 22249-043- 003 006 009 012 015 018 ResinLD200 ECD330 ECD330 ECD330 ECD330 ECD330 % LDPE 100 80 60 40 20 0 CoatWeight (g/m²) Temp. (° C.) 25 25 25 25 25 25 Hot Tack (N) 80 0.07 850.04 90 0.02 0.04 0.02 0.02 0.02 0.10 95 0.10 2.71 3.60 4.72 5.45 5.86100 4.02 6.49 7.26 6.21 6.10 8.00 105 5.96 7.85 7.69 7.25 7.12 8.42 1105.41 7.29 8.99 8.40 7.84 10.32 115 5.00 6.19 7.05 8.82 10.02 10.19 1204.53 5.58 6.97 7.53 7.84 8.50 125 4.18 4.84 5.99 6.21 6.72 7.59 130 3.614.84 4.92 5.96 7.42 Heat Seal (lbs) 85 0.15 0.13 0.13 0.14 0.32 90 0.711.47 1.66 1.35 1.77 3.26 95 0.98 1.41 2.64 1.73 2.40 4.97 100 1.68 2.103.04 2.31 2.69 5.63 105 3.05 2.90 3.75 3.31 3.10 4.94 110 3.44 3.56 3.804.15 3.79 5.66 115 3.26 3.45 4.14 3.59 4.29 120 3.10 3.42 3.76 3.53 3.89125 3.65 130 3.64

TABLE XVIb Hot tack and heat seal data for competitive resins at 25 g/m²coating weight. Notebook 22249-043- 021 024 027 030 033 036 Resin Exact3040 Dow3010 PT1450 PT1450 Nova61C UL02020 % LDPE 20 20 20 Coat Weight(g/m²) Temp. (° C.) 25 25 25 25 25 25 Hot Tack (N) 60 0.07 65 2.46 704.53 75 6.02 80 0.02 0.03 0.02 5.64 85 2.73 1.66 0.27 5.13 90 7.30 0.023.58 2.53 4.61 95 9.32 0.02 4.58 4.41 4.13 100 10.36 0.02 5.42 5.39 0.02105 10.11 2.94 6.46 6.19 0.23 110 8.69 6.50 6.38 7.26 5.70 115 7.06 7.536.57 7.08 7.11 120 6.07 8.14 6.35 6.72 7.73 125 4.53 8.73 4.17 4.67 6.29130 3.80 9.18 3.77 3.99 5.99 135 7.76 Heat Seal (lbs) 60 1.04 65 2.00 702.93 75 0.11 0.24 2.98 80 1.60 0.96 3.59 85 3.26 1.32 0.55 3.51 90 4.551.58 1.05 3.24 95 5.52 0.08 1.66 1.39 0.09 2.80 100 5.29 0.14 1.86 1.650.23 105 5.24 0.27 2.34 1.86 0.32 110 0.90 2.47 1.01 115 2.57 2.30 4.04120 3.03 2.61 4.04 125 4.24 4.46 130 4.34 4.52

TABLE XVIIa Hot tack and heat seal data for ECD-330/LDPE blends at 50g/m² coating weights Notebook 22249-043- 004 007 010 013 016 019 ResinLD200 ECD330 ECD330 ECD330 ECD330 ECD330 % LDPE 100 80 60 40 20 0 CoatWeight (g/m²) Temp. (° C.) 50 50 50 50 50 50 Hot Tack (N) 80 85 90 0.020.04 0.03 0.02 0.02 0.02 95 0.02 0.57 1.56 0.47 4.92 5.53 100 2.34 3.825.66 6.40 7.59 8.58 105 4.19 6.11 8.67 8.72 9.02 10.41 110 3.96 8.6210.20 10.26 10.46 10.66 115 3.76 7.24 7.54 9.42 10.50 10.55 120 3.856.53 7.21 8.36 9.17 10.21 125 3.74 5.96 6.40 7.78 8.62 8.79 130 3.625.67 6.36 6.82 7.27 6.78 Heat Seal (lbs) 85 0.11 0.08 90 0.19 0.09 0.240.08 0.18 0.91 95 1.09 1.71 2.08 2.36 2.61 4.50 100 2.04 2.54 3.01 4.413.82 5.22 105 3.55 3.89 4.33 3.89 4.46 6.13 110 4.46 5.14 4.96 4.52 4.406.26 115 5.34 5.85 6.55 6.53 4.84 7.03 120 5.63 5.86 5.96 6.32 5.45 7.34125 4.31 4.85 5.18 5.30 6.34

TABLE XVIIb Hot tack and heat seal data for competitive resins at 50g/m² coating weight. Notebook 22249-043- 022 025 028 031 034 037 ResinExact 3040 Dow3010 PT1450 PT1450 Nova61C UL02020 % LDPE 20 20 20 CoatWeight (g/m²) Temp. (° C.) 50 50 50 50 50 50 Hot Tack (N) 60 0.037 652.058 70 3.646 75 5.256 80 0.018 0.025 6.67 85 3.697 2.384 6.73 90 8.3440.024 3.582 0.793 5.882 95 10.521 0.025 4.957 4.253 5.569 100 10.3440.022 6.224 4.809 0.025 105 9.931 2.714 7.906 7.726 0.025 110 9.0115.772 7.642 8.934 3.275 115 7.795 8.005 7.443 8.524 5.517 120 6.96 9.7676.806 7.703 7.272 125 6.47 10.693 6.42 6.483 7.835 130 6.028 10.7036.694 135 8.18 5.232 140 6.802 Heat Seal (lbs) 60 0.64 65 2.27 70 3.8475 4.35 80 0.14 0.17 0.18 4.59 85 3.48 1.58 1.33 4.67 90 5.00 2.37 2.254.36 95 6.57 0.05 2.80 2.64 100 6.33 0.06 2.98 2.91 0.19 105 6.69 0.163.11 3.09 0.13 110 0.22 3.34 3.45 0.31 115 0.36 4.00 3.37 0.46 120 2.693.85 3.67 4.34 125 4.95 6.61 130 5.36 6.01 135 5.66 7.59 140 6.29

Additionally, Environmental Stress Crack Resistance can be important forcontaining fatty products, detergents, or other similarly aggressivechemicals. In general, the linear polymers display high ESCR relative toconventional coating polymers. Additionally, ESCR is improved byreducing the crystallinity of the coating polymer. At less than 60% LDPEaddition, the 0.912 density mVLDPE produced ESCR results of greater than1000 hours.

TABLE XVIII Environmental Stress Crack Resistance (ASTM D-1693, F50,hours) % LD-200 ECD-137 ECD-330 0 600.000 >1000 25 410.000 >1000 30120.000 >1000 40 96.000 >1000 60 135.000 190.000 75 68.000 43.000 10090.000 90.000

In use in extrusion coating applications, the LDPE/mVLDPE blends arebelieved to show some or all of the following advantages over prior artmaterials: improved mechanical properties relative to LDPE and LLDPE;improved sealing performance relative to LDPE and LLDPE; at leastequivalent processability to LLDPE; better adhesion to polypropylenerelative to LDPE or LLDPE, thus eliminating or reducing the need foradhesive or tie layers; improved sealing performance relative to LDPEwhen used as a minor component; potentially can be coated in thinnerproducts than LDPE or LLDPE, due to the additional integrity added bythe VLDPE; and better organoleptics than LLDPE, and at least equivalentto or better than LDPE.

EXAMPLE 9

Monolayer films were made using either a VLDPE or an inventive blend ofa VLPDE and a LDPE were made. Sample 1 comprised a m-VLDPE (EXCEED™321,density 0.912 g/cm³) made in a gas phase polymerization process. Sample2 comprised a blend of 90% by weight of a m-VLDPE (EXCEED™ 321, density0.912 g/Cm³) made in a gas phase polymerization process and 10% byweight of a low density polyethylene (ExxonMobil LD200.48, density0.915, melt index 7.5 g/10 min). Sample 3 comprised a blend of 80% byweight of a m-VLDPE (EXCEED™ 321, density 0.912 g/cm³) made in a gasphase polymerization process and 20% by weight of a low densitypolyethylene (ExxonMobil LD200.48, density 0.915, melt index 7.5 g/10min). Sample 4 comprised a blend of 90% by weight of a m-VLDPE (EXCEED™321, density 0.912 g/cm³) made in a gas phase polymerization process and10% by weight of a low density polyethylene (ExxonMobil LD140.09,density 0.919, melt index 0.75 g/10 min). Sample 5 comprised a blend of80% by weight of a m-VLDPE (EXCEED™ 321, density 0.912 g/cm³) made in agas phase polymerization process and 20% by weight of a low densitypolyethylene (ExxonMobil LD140.09, density 0.919, melt index 0.75 g/10min). Table XIX shows the properties of the monolayer films.

TABLE XIX Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 mVLDPE, % 100%90% 80% 90% 80% (ECD- (ECD- (ECD- (ECD- (ECD- 321) 321) 321) 321) 321)LDPE, %  0% 10% 20% 10% 20% (LD200.48) (LD200.48) (LD140.09) (LD140.09)Procesing: Melt Temp, deg F. 385 382 379 382 382 Head Pressure, psi 35203410 3310 3590 3650 Extruder Horsepower 13.6 12.8 11.6 12.5 12.8Extruder Motor Load, % 55.4 50 45.4 50.8 49.9 Production Rate, lb/hr 155156 155 154 157 Film Properties Tensile @ Yield, psi MD 1,078 1,2771,483 1,335 1,533 TD 1,080 1,336 1,340 1,359 1,467 at 200% MD 1,9112,419 3,133 2,973 3,821 Ultimate Tensile, psi MD 11,232 9,882 8,80510,237 9,639 TD 9,197 8,936 8,402 9,176 8,860 Break Elongation, % MD 474503 487 493 462 TD 617 626 636 622 643 1% Secant Modulus, psi MD 25,30031,520 34,470 34,750 38,380 TD 27,500 39,480 45,230 45,170 48,550Elmendorf Tear, g/mil MD 202 133 73 107 48 TD 396 499 649 637 567 DartDrop, g/mil 623 765 379 767 266 (method A) Gauge, mil (avg.) 1.24 1.291.29 1.26 1.30 Haze, % 7.7 2.4 6.6 2.0 2.8 Gloss 45 degree 58 84 63 8683 Puncture Peak Force, lb/mil 11.55 9.92 10.59 11.00 10.00 BreakEnergy,in- 40.40 30.94 30.88 30.89 23.25 lb/mil Total Energy,ft/lb >Capacity >Capacity 2.31 >Capacity 2.19 Room Temp 3.01 1.62 1.741.48 1.82 −29 Degrees F. Shrink, % MD 42 66 74 74 82 TD −4 −18 −17 −17−17

EXAMPLE 10

Monolayer films were made using either an inventive VLDPE, aconventional VLDPE, a blend of an inventive VLPDE and a LDPE, or a blenda conventional VLPDE and a LDPE were made. Sample 6 comprised a m-VLDPE(EXCEED™ 321, density 0.912 g/cm³) made in a gas phase polymerizationprocess. Sample 7 comprised an inventive blend of 90% by weight of am-VLDPE (EXCEED™ 321, density 0.912 g/cm³) made in a gas phasepolymerization process and 10% by weight of a low density polyethylene(ExxonMobil LD200.48, density 0.915, melt index 7.5 g/10 min.). Sample 8comprised an inventive blend of 90% by weight of a m-VLDPE (EXCEED™ 321,density 0.912 g/cm³) made in a gas phase polymerization process and 10%by weight of a low density polyethylene (ExxonMobil LD140.09, density0.919, melt index 0.75 g/10 min), Sample 9 (comparative) comprised ablend of 90% by weight of a VLDPE (Dow Attane 4201, density 0.9132g/cm³) made in a solution polymerization process and 10% by weight of alow density polyethylene (ExxonMobil LD200.48, density 0.915, melt index7.5 g/10 min). Sample 10 (comparative) comprised a blend of 90% byweight of a VLDPE (Dow Attane 4201, density 0.9132 g/cm³) made in asolution polymerization process and 10% by weight of a low densitypolyethylene (ExxonMobil LD140.09, density 0.919, melt index 0.75 g/10min). Sample 6 (comparative) comprised a VLDPE (Dow Attane 4201, density0.9132 g/cm³) made in a solution polymerization process.

Table XX shows the haze and gloss properties of the monolayer films.Samples 7 and 8 showed that the inventive blends comprising a VLDPE anda LDPE had clearer optical properties (i.e. lower haze and higher gloss)than the blends comprising a conventional VLDPE and a LDPE of Samples 9and 10.

TABLE XX Sample 9 Sample 10 Sample 11 Sample 6 Sample 7 Sample 8Comparative Comparative Comparative VLDPE, % 100% 90% 90% 90% 90% 100%(ECD- (ECD- (ECD- (Attane- (Attane- (Attane- 321) 321) 321) 4201) 4201)4201) LDPE, %  0% 10% 10% 10% 10%  0% (LD200.48) (LD140.09) (LD200.48)(LD140.09) Haze, % 7.7 2.4 2.0 >4 >2.5 6.9 Gloss, 45 58 84 86 <80 <84 70deg. 1.24 1.29 1.26 target 1.25 target 1.25 1.25 Gauge, avg. mil

EXAMPLE 11

Peel tests were conducted to determine the adhesion of the 50 g/m²coatings to the OPP/aluminum substrate (polyethylene coatings on the OPPside of the substrate). Fifteen (15) mm wide specimens were cut in themachine direction of the samples. The polyethylene coating was peeledmanually from the substrate to allow the coating and substrate to beclamped into opposing grips on a tensile tester. The grips are separatedat a rate of 100 mm/minute and the force to delaminate is measured.Table XXI shows the results of the peel test. Only the LD200, Dow 3010,and LD261 samples could be peeled from the OPP. The other resins couldnot be peeled without tearing the substrate or causing delaminationbetween the OPP and aluminum layers. The single-site catalyzed resins,ECD-330, Exact 3040, and Affinity PT1450, all had better adhesion to theOPP than the conventional LDPE, LLDPE, or EVA. It is interesting to notethat Nova Sclair 61C LLDPE also had good adhesion to the OPP. Onepossible explanation is excessive oxidation in the Nova product due tovery high extrusion temperatures, 332° C., which could have resulted ingood adhesion.

TABLE XXI Peel Results (N/15 mm) m-VLDPE not measurable (ECD-330) LDPE0.40 (ExxonMobil LD200) (1 sample, all others pulled apart easily) LLDPE0.47 (Dow 3010) (average of 4 samples) LEVA 0.06 (ExxonMobil LD261)(average of 4 samples) Plastomer not measurable (Exxxon Mobil Exact3040) Plastomer) not measurable Dow Affinity PT1450. LLDPE notmeasurable (Nova Sclair 61C LLDPE)

All patents, test procedures, and other documents cited herein,including priority documents, in this application are fully incorporatedby reference to the extent such disclosure is not inconsistent with thisapplication and for all jurisdictions in which such incorporation ispermitted.

What is claimed is:
 1. A polymer blend comprising: (a) from 1 to 99% byweight of a copolymer derived from ethylene and one or more C₃-C₂₀ alphaolefin comonomers, said copolymer having: (i) a comonomer content offrom 5 to 15 wt. %, (ii) a density of less than 0.916 g/cm³, (iii) acomposition distribution breadth index in the range of from 55% to 70%,(iv) a molecular weight distribution Mw/Mn of from 2 to 3, (v) amolecular weight distribution Mz/Mw of less than 2; and (b) from 1 to99% by weight of a low density polyethylene polymer having a density offrom 0.916 to 0.928 g/cm³, wherein the sum of (a) and (b) is 100%. 2.The polymer blend of claim 1, wherein the copolymer has a melt indexfrom 6 to 15 dg/min.
 3. The polymer blend of claim 1, wherein thecopolymer has melt index from 9 to 12 dg/min.
 4. The polymer blend ofclaim 1, wherein the copolymer is a linear polymer.
 5. The polymer blendof claim 1, wherein the blend comprises from 5 to 95% by weight of thelow density polyethylene low density polyethylene polymer.
 6. Thepolymer blend of claim 1, wherein the blend comprises from 5 to 35% byweight of the low density polyethylene polymer.
 7. The polymer blend ofclaim 1, wherein the copolymer is a copolymer of ethylene and a C₃ toC₁₂ alpha-olefin.
 8. The polymer blend of claim 1, wherein the copolymeris produced using a unbridged bis-Cp metallocene catalyst system.
 9. Thepolymer blend of claim 1, wherein the copolymer is produced in a gasphase polymerization process.
 10. The polymer blend of claim 1, whereinthe copolymer is produced in a gas phase polymerization process at apressure in the range of from 100 psig to 1000 psig.
 11. The polymerblend of claim 1, wherein the copolymer is produced using an unbridgedbis-Cp metallocene catalyst system in a gas phase polymerization processat a pressure an the range of from 100 psig to 1000 psig.
 12. A polymerblend composition, comprising: (i) a copolymer derived from ethylene andone or more C₃-C₁₀ alpha olefin comonomers, said copolymer having: (a) acomonomer content of from 5 to 15 wt. %, (b) a density of less than0.916 g/cm³, (c) a composition distribution breadth index in the rangeof from 55% to70%, (d) a molecular weight distribution Mw/Mn of from 2to 3, (e) a molecular weight distribution Mz/Mw of less than 2, and (f)a bi-model composition distribution; and (ii) a low density polyethylenepolymer having a density of from 0.916 to 0.928 g/cm³.
 13. A monolayerfilm comprising a polymer blend composition, the polymer blendcomposition comprising: (i) a copolymer derived form ethylene and one ormore C3-C20 alpha olefin comonomer, said copolymer having: (a) acomonomer content of from 5 to 15 wt. %, (b) a density of less than0.916 0.928 g/cm³, (c) a composition distribution breadth index in therange of from 55% to 70%, (d) a molecular weight distribution Mw/Mn offrom 2 to 3, (e) a molecular weight distribution Mz/Mw of less than 2,and (f) a bi-modal composition distribution; and (ii) a low densitypolyethylene polymer having a density of from 0.916 to 0.9280.928 g/cm³.14. The polymer blend composition of claim 12, wherein the copolymer hasa melt index of 5 dg/min or less.
 15. The polymer blend composition ofclaim 12, wherein the copolymer is a linear polymer.
 16. The polymerblend composition of claim 12, wherein a bi-modal compositiondistribution is determined by two peaks in a TREF measurement.
 17. Thepolymer blend composition of claim 12, wherein the blend comprises from5 to 95% by weight of the low density polyethylene polymer.
 18. Thepolymer blend composition of claim 12, wherein the blend comprises from5 to 35% by weight of the low density polyethylene polymer.
 19. Thepolymer blend composition of claim 12, wherein the copolymer is acopolymer of ethylene and a C₃ to C₁₂ alpha-olefin.
 20. The polymerblend composition of claim 12, wherein the copolymer is produced usingan unbridged bis-Cp metallocene catalyst system.
 21. The polymer blendcomposition of claim 12, wherein the copolymer is produced in a gasphase polymerization process.
 22. The polymer blend composition of claim12, wherein the copolymer is produced in a gas phase polymerizationprocess at a pressure in the range of from 100 psig to 1000 psig. 23.The polymer blend composition of claim 12, wherein the copolymer isproduced using an unbridged bis-Cp metallocene catalyst system in a gasphase polymerization process at a pressure in the range of front 100psig to 1000 psig.
 24. The monolayer film of claim 13, wherein thecopolymer has a melt index of 5 dg/min or legs.
 25. The monolayer filmof claim 13, wherein the copolymer is a linear polymer.
 26. Themonolayer film of claim 13, wherein a bi-modal composition distributionis determined by two peaks in a TREF measurement.
 27. The monolayer filmof claim 13, wherein the blend comprises from 5 to 95% by weight of thelow density polyethylene polymer.
 28. The monolayer film of claim 13,wherein the blend comprises from 5 to 35% by weight of the low densitypolyethylene polymer.
 29. The monolayer film of claim 13, wherein thecopolymer is a copolymer of ethylene and a C₃ to C12 alpha-olefin. 30.The monolayer film of claim 13, wherein the copolymer is produced usingan unbridged bis-Cp metallocene catalyst system.
 31. The monolayer filmof claim 13, wherein the copolymer is produced in a gas phasepolymerization process.
 32. The monolayer film of claim 13, wherein thecopolymer is produced in gas phase polymerization process at a pressurein the range of from 100 psig to 1000 psig.
 33. The monolayer film ofclaim 13, wherein the copolymer is produced using an unbridged bis-Cpmetallocene catalyst system in a gas phase polymerization process at apressure in the range of from 100 psig to 1000 psig.